Import sendmail 8.16.1

[FreeBSD/FreeBSD.git] / src / README

# Copyright (c) 1998-2004 Proofpoint, Inc. and its suppliers.
#       All rights reserved.
# Copyright (c) 1983, 1995-1997 Eric P. Allman.  All rights reserved.
# Copyright (c) 1988
#       The Regents of the University of California.  All rights reserved.
#
# By using this file, you agree to the terms and conditions set
# forth in the LICENSE file which can be found at the top level of
# the sendmail distribution.
#
#
#       $Id: README,v 8.393 2013-11-22 20:51:54 ca Exp $
#

This directory contains the source files for sendmail(TM).

   *******************************************************************
   !! Read sendmail/SECURITY for important installation information !!
   *******************************************************************

        **********************************************************
        **  Read below for more details on building sendmail.   **
        **********************************************************

**************************************************************************
**  IMPORTANT:  Read the appropriate paragraphs in the section on       **
**  ``Operating System and Compile Quirks''.                            **
**************************************************************************

For detailed instructions, please read the document ../doc/op/op.me:

        cd ../doc/op ; make op.ps op.txt

Sendmail is a trademark of Proofpoint, Inc.
US Patent Numbers 6865671, 6986037.


+-------------------+
| BUILDING SENDMAIL |
+-------------------+

By far, the easiest way to compile sendmail is to use the "Build"
script:

        sh ./Build

This uses the "uname" command to figure out what architecture you are
on and creates a proper Makefile accordingly.  It also creates a
subdirectory per object format, so that multiarchitecture support is
easy.  In general this should be all you need.  IRIX 6.x users should
read the note below in the OPERATING SYSTEM AND COMPILE QUIRKS section.

If you need to look at other include or library directories, use the
-I or -L flags on the command line, e.g.,

        sh ./Build -I/usr/sww/include -L/usr/sww/lib

It's also possible to create local site configuration in the file
site.config.m4 (or another file settable with the -f flag).  This
file contains M4 definitions for various compilation values; the
most useful are:

confMAPDEF      -D flags to specify database types to be included
                (see below)
confENVDEF      -D flags to specify other environment information
confINCDIRS     -I flags for finding include files during compilation
confLIBDIRS     -L flags for finding libraries during linking
confLIBS        -l flags for selecting libraries during linking
confLDOPTS      other ld(1) linker options

Others can be found by examining Makefile.m4.  Please read
../devtools/README for more information about the site.config.m4
file.

You can recompile from scratch using the -c flag with the Build
command.  This removes the existing compilation directory for the
current platform and builds a new one.  The -c flag must also
be used if any site.*.m4 file in devtools/Site/ is changed.

Porting to a new Unix-based system should be a matter of creating
an appropriate configuration file in the devtools/OS/ directory.


+----------------------+
| DATABASE DEFINITIONS |
+----------------------+

There are several database formats that can be used for the alias files
and for general maps.  When used for alias files they interact in an
attempt to be backward compatible.

The options are:

CDB             Constant DataBase, requires tinycdb (0.75), see
                http://www.corpit.ru/mjt/tinycdb.html
                CDB is included automatically if the Build script can find
                a library named libcdb.a or libcdb.so.
                By default, .cdb is used as extension for cdb maps, however,
                if CDB is set to 2, then .db is used to make transition from
                hash maps easier.  Note: this usually requires to exclude cdb
                from confLIBSEARCH, see devtools/README.
NEWDB           The new Berkeley DB package.  Some systems (e.g., BSD/OS and
                Digital UNIX 4.0) have some version of this package
                pre-installed.  If your system does not have Berkeley DB
                pre-installed, or the version installed is not version 2.0
                or greater (e.g., is Berkeley DB 1.85 or 1.86), get the
                current version from http://www.sleepycat.com/.  DO NOT
                use a version from any of the University of California,
                Berkeley "Net" or other distributions.  If you are still
                running BSD/386 1.x, you will need to upgrade the included
                Berkeley DB library to a current version.  NEWDB is included
                automatically if the Build script can find a library named
                libdb.a or libdb.so.
                See also OPERATING SYSTEM AND COMPILE QUIRKS about Berkeley
                DB versions, e.g., DB 4.1.x.
NDBM            The older NDBM implementation -- the very old V7 DBM
                implementation is no longer supported.
NIS             Network Information Services.  To use this you must have
                NIS support on your system.
NISPLUS         NIS+ (the revised NIS released with Solaris 2).  You must
                have NIS+ support on your system to use this flag.
HESIOD          Support for Hesiod (from the DEC/Athena distribution).  You
                must already have Hesiod support on your system for this to
                work.  You may be able to get this to work with the MIT/Athena
                version of Hesiod, but that's likely to be a lot of work.
                BIND 8.X also includes Hesiod support.
LDAPMAP         Lightweight Directory Access Protocol support.  You will
                have to install the UMich or OpenLDAP
                (http://www.openldap.org/) ldap and lber libraries to use
                this flag.
MAP_REGEX       Regular Expression support.  You will need to use an
                operating system which comes with the POSIX regex()
                routines or install a regexp library such as libregex from
                the Free Software Foundation.
DNSMAP          DNS map support.  Requires NAMED_BIND.
PH_MAP          PH map support.  You will need the libphclient library from
                the nph package (http://www-dev.cites.uiuc.edu/ph/nph/).
MAP_NSD         nsd map support (IRIX 6.5 and later).
SOCKETMAP       Support for a trivial query protocol over UNIX domain or TCP
                sockets.

>>>  NOTE WELL for NEWDB support: If you want to get ndbm support, for
>>>  Berkeley DB versions under 2.0, it is CRITICAL that you remove
>>>  ndbm.o from libdb.a before you install it and DO NOT install ndbm.h;
>>>  for Berkeley DB versions 2.0 through 2.3.14, remove dbm.o from libdb.a
>>>  before you install it.  If you don't delete these, there is absolutely
>>>  no point to including -DNDBM, since it will just get you another
>>>  (inferior) API to the same format database.  These files OVERRIDE
>>>  calls to ndbm routines -- in particular, if you leave ndbm.h in,
>>>  you can find yourself using the new db package even if you don't
>>>  define NEWDB.  Berkeley DB versions later than 2.3.14 do not need
>>>  to be modified.  Please also consult the README in the top level
>>>  directory of the sendmail distribution for other important information.
>>>
>>>  Further note: DO NOT remove your existing /usr/include/ndbm.h --
>>>  you need that one.  But do not install an updated ndbm.h in
>>>  /usr/include, /usr/local/include, or anywhere else.

If NEWDB and NDBM are defined (but not NIS), then sendmail will read
NDBM format alias files, but the next time a newaliases is run the
format will be converted to NEWDB; that format will be used forever
more.  This is intended as a transition feature.

If NEWDB, NDBM, and NIS are all defined and the name of the file includes
the string "/yp/", sendmail will rebuild BOTH the NEWDB and NDBM format
alias files.  However, it will only read the NEWDB file; the NDBM format
file is used only by the NIS subsystem.  This is needed because the NIS
maps on an NIS server are built directly from the NDBM files.

If NDBM and NIS are defined (regardless of the definition of NEWDB),
and the filename includes the string "/yp/", sendmail adds the special
tokens "YP_LAST_MODIFIED" and "YP_MASTER_NAME", both of which are
required if the NDBM file is to be used as an NIS map.

All of these flags are normally defined in a confMAPDEF setting in your
site.config.m4.

If you define NEWDB or HESIOD you get the User Database (USERDB)
automatically.  Generally you do want to have NEWDB for it to do
anything interesting.  See above for getting the Berkeley DB
package (i.e., NEWDB).  There is no separate "user database"
package -- don't bother searching for it on the net.

Hesiod and LDAP require libraries that may not be installed with your
system.  These are outside of my ability to provide support.  See the
"Quirks" section for more information.

The regex map can be used to see if an address matches a certain regular
expression.  For example, all-numerics local parts are common spam
addresses, so "^[0-9]+$" would match this.  By using such a map in a
check_* rule-set, you can block a certain range of addresses that would
otherwise be considered valid.

The socket map uses a simple request/reply protocol over TCP or
UNIX domain sockets to query an external server. Both requests and
replies are text based and encoded as netstrings.  The socket map
uses the same syntax as milters the specify the remote endpoint,
e.g.:

KmySocketMap socket inet:12345@127.0.0.1

See doc/op/op.me for details.


+---------------+
| COMPILE FLAGS |
+---------------+

Wherever possible, I try to make sendmail pull in the correct
compilation options needed to compile on various environments based on
automatically defined symbols.  Some machines don't seem to have useful
symbols available, requiring that a compilation flag be defined in
the Makefile; see the devtools/OS subdirectory for the supported
architectures.

If you are a system to which sendmail has already been ported you
should not have to touch the following symbols.  But if you are porting,
you may have to tweak the following compilation flags in conf.h in order
to get it to compile and link properly:

SYSTEM5         Adjust for System V (not necessarily Release 4).
SYS5SIGNALS     Use System V signal semantics -- the signal handler
                is automatically dropped when the signal is caught.
                If this is not set, use POSIX/BSD semantics, where the
                signal handler stays in force until an exec or an
                explicit delete.  Implied by SYSTEM5.
SYS5SETPGRP     Use System V setpgrp() semantics.  Implied by SYSTEM5.
HASNICE         Define this to zero if you lack the nice(2) system call.
HASRRESVPORT    Define this to zero if you lack the rresvport(3) system call.
HASFCHMOD       Define this to one if you have the fchmod(2) system call.
                This improves security.
HASFCHOWN       Define this to one if you have the fchown(2) system call.
                This is required for the TrustedUser option if sendmail
                must rebuild an (alias) map.
HASFLOCK        Set this if you prefer to use the flock(2) system call
                rather than using fcntl-based locking.  Fcntl locking
                has some semantic gotchas, but many vendor systems
                also interface it to lockd(8) to do NFS-style locking.
                Unfortunately, may vendors implementations of fcntl locking
                is just plain broken (e.g., locks are never released,
                causing your sendmail to deadlock; when the kernel runs
                out of locks your system crashes).  For this reason, I
                recommend always defining this unless you are absolutely
                certain that your fcntl locking implementation really works.
HASUNAME        Set if you have the "uname" system call.  Implied by
                SYSTEM5.
HASUNSETENV     Define this if your system library has the "unsetenv"
                subroutine.
HASSETSID       Define this if you have the setsid(2) system call.  This
                is implied if your system appears to be POSIX compliant.
HASINITGROUPS   Define this if you have the initgroups(3) routine.
HASSETVBUF      Define this if you have the setvbuf(3) library call.
                If you don't, setlinebuf will be used instead.  This
                defaults on if your compiler defines __STDC__.
HASSETREUID     Define this if you have setreuid(2) ***AND*** root can
                use setreuid to change to an arbitrary user.  This second
                condition is not satisfied on AIX 3.x.  You may find that
                your system has setresuid(2), (for example, on HP-UX) in
                which case you will also have to #define setreuid(r, e)
                to be the appropriate call.  Some systems (such as Solaris)
                have a compatibility routine that doesn't work properly,
                but may have "saved user ids" properly implemented so you
                can ``#define setreuid(r, e) seteuid(e)'' and have it work.
                The important thing is that you have a call that will set
                the effective uid independently of the real or saved uid
                and be able to set the effective uid back again when done.
                There's a test program in ../test/t_setreuid.c that will
                try things on your system.  Setting this improves the
                security, since sendmail doesn't have to read .forward
                and :include: files as root.  There are certain attacks
                that may be unpreventable without this call.
USESETEUID      Define this to 1 if you have a seteuid(2) system call that
                will allow root to set only the effective user id to an
                arbitrary value ***AND*** you have saved user ids.  This is
                preferable to HASSETREUID if these conditions are fulfilled.
                These are the semantics of the to-be-released revision of
                Posix.1.  The test program ../test/t_seteuid.c will try
                this out on your system.  If you define both HASSETREUID
                and USESETEUID, the former is ignored.
HASSETEGID      Define this if you have setegid(2) and it can be
                used to set the saved gid.  Please run t_dropgid in
                test/ if you are not sure whether the call works.
HASSETREGID     Define this if you have setregid(2) and it can be
                used to set the saved gid.  Please run t_dropgid in
                test/ if you are not sure whether the call works.
HASSETRESGID    Define this if you have setresgid(2) and it can be
                used to set the saved gid.  Please run t_dropgid in
                test/ if you are not sure whether the call works.
HASLSTAT        Define this if you have symbolic links (and thus the
                lstat(2) system call).  This improves security.  Unlike
                most other options, this one is on by default, so you
                need to #undef it in conf.h if you don't have symbolic
                links (these days everyone does).
HASSETRLIMIT    Define this to 1 if you have the setrlimit(2) syscall.
                You can define it to 0 to force it off.  It is assumed
                if you are running a BSD-like system.
HASULIMIT       Define this if you have the ulimit(2) syscall (System V
                style systems).  HASSETRLIMIT overrides, as it is more
                general.
HASWAITPID      Define this if you have the waitpid(2) syscall.
HASGETDTABLESIZE
                Define this if you have the getdtablesize(2) syscall.
HAS_GETHOSTBYNAME2      Define this to 1 if your system supports
                gethostbyname2(2).
HAS_ST_GEN      Define this to 1 if your system has the st_gen field in
                the stat structure (see stat(2)).
HASSRANDOMDEV   Define this if your system has the srandomdev(3) function
                call.
HASURANDOMDEV   Define this if your system has /dev/urandom(4).
HASSTRERROR     Define this if you have the libc strerror(3) function (which
                should be declared in <errno.h>), and it should be used
                instead of sys_errlist.
HASCLOSEFROM    Define this if your system has closefrom(3).
HASFDWALK       Define this if your system has fdwalk(3).
SM_CONF_GETOPT  Define this as 0 if you need a reimplementation of getopt(3).
                On some systems, getopt does very odd things if called
                to scan the arguments twice.  This flag will ask sendmail
                to compile in a local version of getopt that works
                properly.  You may also need this if you build with
                another library that introduces a non-standard getopt(3).
NEEDSTRTOL      Define this if your standard C library does not define
                strtol(3).  This will compile in a local version.
NEEDFSYNC       Define this if your standard C library does not define
                fsync(2).  This will try to simulate the operation using
                fcntl(2); if that is not available it does nothing, which
                isn't great, but at least it compiles and runs.
HASGETUSERSHELL Define this to 1 if you have getusershell(3) in your
                standard C library.  If this is not defined, or is defined
                to be 0, sendmail will scan the /etc/shells file (no
                NIS-style support, defaults to /bin/sh and /bin/csh if
                that file does not exist) to get a list of unrestricted
                user shells.  This is used to determine whether users
                are allowed to forward their mail to a program or a file.
NEEDPUTENV      Define this if your system needs am emulation of the
                putenv(3) call.  Define to 1 to implement it in terms
                of setenv(3) or to 2 to do it in terms of primitives.
NOFTRUNCATE     Define this if you don't have the ftruncate(2) syscall.
                If you don't have this system call, there is an unavoidable
                race condition that occurs when creating alias databases.
GIDSET_T        The type of entries in a gidset passed as the second
                argument to getgroups(2).  Historically this has been an
                int, so this is the default, but some systems (such as
                IRIX) pass it as a gid_t, which is an unsigned short.
                This will make a difference, so it is important to get
                this right!  However, it is only an issue if you have
                group sets.
SLEEP_T         The type returned by the system sleep() function.
                Defaults to "unsigned int".  Don't worry about this
                if you don't have compilation problems.
ARBPTR_T        The type of an arbitrary pointer -- defaults to "void *".
                If you are an very old compiler you may need to define
                this to be "char *".
SOCKADDR_LEN_T  The type used for the third parameter to accept(2),
                getsockname(2), and getpeername(2), representing the
                length of a struct sockaddr.  Defaults to int.
SOCKOPT_LEN_T   The type used for the fifth parameter to getsockopt(2)
                and setsockopt(2), representing the length of the option
                buffer.  Defaults to int.
LA_TYPE         The type of load average your kernel supports.  These
                can be one of:
                 LA_ZERO (1) -- it always returns the load average as
                        "zero" (and does so on all architectures).
                 LA_INT (2) to read /dev/kmem for the symbol avenrun and
                        interpret as a long integer.
                 LA_FLOAT (3) same, but interpret the result as a floating
                        point number.
                 LA_SHORT (6) to interpret as a short integer.
                 LA_SUBR (4) if you have the getloadavg(3) routine in your
                        system library.
                 LA_MACH (5) to use MACH-style load averages (calls
                        processor_set_info()),
                 LA_PROCSTR (7) to read /proc/loadavg and interpret it
                        as a string representing a floating-point
                        number (Linux-style).
                 LA_READKSYM (8) is an implementation suitable for some
                        versions of SVr4 that uses the MIOC_READKSYM ioctl
                        call to read /dev/kmem.
                 LA_DGUX (9) is a special implementation for DG/UX that uses
                        the dg_sys_info system call.
                 LA_HPUX (10) is an HP-UX specific version that uses the
                        pstat_getdynamic system call.
                 LA_IRIX6 (11) is an IRIX 6.x specific version that adapts
                        to 32 or 64 bit kernels; it is otherwise very similar
                        to LA_INT.
                 LA_KSTAT (12) uses the (Solaris-specific) kstat(3k)
                        implementation.
                 LA_DEVSHORT (13) reads a short from a system file (default:
                        /dev/table/avenrun) and scales it in the same manner
                        as LA_SHORT.
                 LA_LONGLONG (17) to read /dev/kmem for the symbol avenrun and
                        interpret as a long long integer (e.g., for 64 bit
                        systems).
                LA_INT, LA_SHORT, LA_FLOAT, and LA_READKSYM have several
                other parameters that they try to divine: the name of your
                kernel, the name of the variable in the kernel to examine,
                the number of bits of precision in a fixed point load average,
                and so forth.  LA_DEVSHORT uses _PATH_AVENRUN to find the
                device to be read to find the load average.
                In desperation, use LA_ZERO.  The actual code is in
                conf.c -- it can be tweaked if you are brave.
FSHIFT          For LA_INT, LA_SHORT, and LA_READKSYM, this is the number
                of bits of load average after the binary point -- i.e.,
                the number of bits to shift right in order to scale the
                integer to get the true integer load average.  Defaults to 8.
_PATH_UNIX      The path to your kernel.  Needed only for LA_INT, LA_SHORT,
                and LA_FLOAT.  Defaults to "/unix" on System V, "/vmunix"
                everywhere else.
LA_AVENRUN      For LA_INT, LA_SHORT, and LA_FLOAT, the name of the kernel
                variable that holds the load average.  Defaults to "avenrun"
                on System V, "_avenrun" everywhere else.
SFS_TYPE        Encodes how your kernel can locate the amount of free
                space on a disk partition.  This can be set to SFS_NONE
                (0) if you have no way of getting this information,
                SFS_USTAT (1) if you have the ustat(2) system call,
                SFS_4ARGS (2) if you have a four-argument statfs(2)
                system call (and the include file is <sys/statfs.h>),
                SFS_VFS (3), SFS_MOUNT (4), SFS_STATFS (5) if you have
                the two-argument statfs(2) system call with includes in
                <sys/vfs.h>, <sys/mount.h>, or <sys/statfs.h> respectively,
                or SFS_STATVFS (6) if you have the two-argument statvfs(2)
                call.  The default if nothing is defined is SFS_NONE.
SFS_BAVAIL      with SFS_4ARGS you can also set SFS_BAVAIL to the field name
                in the statfs structure that holds the useful information;
                this defaults to f_bavail.
SPT_TYPE        Encodes how your system can display what a process is doing
                on a ps(1) command (SPT stands for Set Process Title).  Can
                be set to:
                SPT_NONE (0) -- Don't try to set the process title at all.
                SPT_REUSEARGV (1) -- Pad out your argv with the information;
                        this is the default if none specified.
                SPT_BUILTIN (2) -- The system library has setproctitle.
                SPT_PSTAT (3) -- Use the PSTAT_SETCMD option to pstat(2)
                        to set the process title; this is used by HP-UX.
                SPT_PSSTRINGS (4) -- Use the magic PS_STRINGS pointer (4.4BSD).
                SPT_SYSMIPS (5) -- Use sysmips() supported by NEWS-OS 6.
                SPT_SCO (6) -- Write kernel u. area.
                SPT_CHANGEARGV (7) -- Write pointers to our own strings into
                        the existing argv vector.
SPT_PADCHAR     Character used to pad the process title; if undefined,
                the space character (0x20) is used.  This is ignored if
                SPT_TYPE != SPT_REUSEARGV
ERRLIST_PREDEFINED
                If set, assumes that some header file defines sys_errlist.
                This may be needed if you get type conflicts on this
                variable -- otherwise don't worry about it.
WAITUNION       The wait(2) routine takes a "union wait" argument instead
                of an integer argument.  This is for compatibility with
                old versions of BSD.
SCANF           You can set this to extend the F command to accept a
                scanf string -- this gives you a primitive parser for
                class definitions -- BUT it can make you vulnerable to
                core dumps if the target file is poorly formed.
SYSLOG_BUFSIZE  You can define this to be the size of the buffer that
                syslog accepts.  If it is not defined, it assumes a
                1024-byte buffer.  If the buffer is very small (under
                256 bytes) the log message format changes -- each
                e-mail message will log many more messages, since it
                will log each piece of information as a separate line
                in syslog.
BROKEN_RES_SEARCH
                On Ultrix (and maybe other systems?) if you use the
                res_search routine with an unknown host name, it returns
                -1 but sets h_errno to 0 instead of HOST_NOT_FOUND.  If
                you set this, sendmail considers 0 to be the same as
                HOST_NOT_FOUND.
NAMELISTMASK    If defined, values returned by nlist(3) are masked
                against this value before use -- a common value is
                0x7fffffff to strip off the top bit.
BSD4_4_SOCKADDR If defined, socket addresses have an sa_len field that
                defines the length of this address.
SAFENFSPATHCONF Set this to 1 if and only if you have verified that a
                pathconf(2) call with _PC_CHOWN_RESTRICTED argument on an
                NFS filesystem where the underlying system allows users to
                give away files to other users returns <= 0.  Be sure you
                try both on NFS V2 and V3.  Some systems assume that their
                local policy apply to NFS servers -- this is a bad
                assumption!  The test/t_pathconf.c program will try this
                for you -- you have to run it in a directory that is
                mounted from a server that allows file giveaway.
SIOCGIFCONF_IS_BROKEN
                Set this if your system has an SIOCGIFCONF ioctl defined,
                but it doesn't behave the same way as "most" systems (BSD,
                Solaris, SunOS, HP-UX, etc.)
SIOCGIFNUM_IS_BROKEN
                Set this if your system has an SIOCGIFNUM ioctl defined,
                but it doesn't behave the same way as "most" systems
                (Solaris, HP-UX).
FAST_PID_RECYCLE
                Set this if your system can reuse the same PID in the same
                second.
SO_REUSEADDR_IS_BROKEN
                Set this if your system has a setsockopt() SO_REUSEADDR
                flag but doesn't pay attention to it when trying to bind a
                socket to a recently closed port.
NEEDSGETIPNODE  Set this if your system supports IPv6 but doesn't include
                the getipnodeby{name,addr}() functions.  Set automatically
                for Linux's glibc.
PIPELINING      Support SMTP PIPELINING (set by default).
USING_NETSCAPE_LDAP
                Deprecated in favor of SM_CONF_LDAP_MEMFREE.  See
                libsm/README.
NEEDLINK        Set this if your system doesn't have a link() call.  It
                will create a copy of the file instead of a hardlink.
USE_ENVIRON     Set this to 1 to access process environment variables from
                the external variable environ instead of the third
                parameter of main().
USE_DOUBLE_FORK By default this is on (1).  Set it to 0 to suppress the
                extra fork() used to avoid intermediate zombies.
ALLOW_255       Do not convert (char)0xff to (char)0x7f in headers etc.
                This can also be done at runtime with the command line
                option -d82.101.
NEEDINTERRNO    Set this if <errno.h> does not declare errno, i.e., if an
                application needs to use
                extern int errno;
USE_TTYPATH     Set this to 1 to enable ErrorMode=write.
USESYSCTL       Use sysctl(3) to determine the number of CPUs in a system.
HASSNPRINTF     Set this to 1 if your OS has a working snprintf(3), i.e.,
                it properly obeys the size of the buffer and returns the
                number of characters that would have been printed if the
                size were unlimited.
LDAP_REFERRALS  Set this if you want to use the -R flag (do not auto chase
                referrals) for LDAP maps (requires -DLDAPMAP).
MILTER_NO_NAGLE Turn off Nagle algorithm for communication with libmilter
                ("cork" on Linux).  On some operating systems this may
                improve the interprocess communication performance.


+-----------------------+
| COMPILE-TIME FEATURES |
+-----------------------+

There are a bunch of features that you can decide to compile in, such
as selecting various database packages and special protocol support.
Several are assumed based on other compilation flags -- if you want to
"un-assume" something, you probably need to edit conf.h.  Compilation
flags that add support for special features include:

CDB             Include support for tinycdb.
NDBM            Include support for "new" DBM library for aliases and maps.
                Normally defined in the Makefile.
NEWDB           Include support for Berkeley DB package (hash & btree)
                for aliases and maps.  Normally defined in the Makefile.
                If the version of NEWDB you have is the old one that does
                not include the "fd" call (this call was added in version
                1.5 of the Berkeley DB code), you must upgrade to the
                current version of Berkeley DB.
NIS             Define this to get NIS (YP) support for aliases and maps.
                Normally defined in the Makefile.
NISPLUS         Define this to get NIS+ support for aliases and maps.
                Normally defined in the Makefile.
HESIOD          Define this to get Hesiod support for aliases and maps.
                Normally defined in the Makefile.
NETINFO         Define this to get NeXT NetInfo support for aliases and maps.
                Normally defined in the Makefile.
LDAPMAP         Define this to get LDAP support for maps.
PH_MAP          Define this to get PH support for maps.
MAP_NSD         Define this to get nsd support for maps.
USERDB          Define this to 1 to include support for the User Information
                Database.  Implied by NEWDB or HESIOD.  You can use
                -DUSERDB=0 to explicitly turn it off.
IDENTPROTO      Define this as 1 to get IDENT (RFC 1413) protocol support.
                This is assumed unless you are running on Ultrix or
                HP-UX, both of which have a problem in the UDP
                implementation.  You can define it to be 0 to explicitly
                turn off IDENT protocol support.  If defined off, the code
                is actually still compiled in, but it defaults off; you
                can turn it on by setting the IDENT timeout in the
                configuration file.
IP_SRCROUTE     Define this to 1 to get IP source routing information
                displayed in the Received: header.  This is assumed on
                most systems, but some (e.g., Ultrix) apparently have a
                broken version of getsockopt that doesn't properly
                support the IP_OPTIONS call.  You probably want this if
                your OS can cope with it.  Symptoms of failure will be that
                it won't compile properly (that is, no support for fetching
                IP_OPTIONs), or it compiles but source-routed TCP connections
                either refuse to open or open and hang for no apparent reason.
                Ultrix and AIX3 are known to fail this way.
LOG             Set this to get syslog(3) support.  Defined by default
                in conf.h.  You want this if at all possible.
NETINET         Set this to get TCP/IP support.  Defined by default
                in conf.h.  You probably want this.
NETINET6        Set this to get IPv6 support.  Other configuration may
                be needed in conf.h for your particular operating system.
                Also, DaemonPortOptions must be set appropriately for
                sendmail to accept IPv6 connections.
NETISO          Define this to get ISO networking support.
NETUNIX         Define this to get Unix domain networking support.  Defined
                by default.  A few bizarre systems (SCO, ISC, Altos) don't
                support this networking domain.
NETNS           Define this to get NS networking support.
NETX25          Define this to get X.25 networking support.
NAMED_BIND      If non-zero, include DNS (name daemon) support, including
                MX support.  The specs say you must use this if you run
                SMTP.  You don't have to be running a name server daemon
                on your machine to need this -- any use of the DNS resolver,
                including remote access to another machine, requires this
                option.  Defined by default in conf.h.  Define it to zero
                ONLY on machines that do not use DNS in any way.
MATCHGECOS      Permit fuzzy matching of user names against the full
                name (GECOS) field in the /etc/passwd file.  This should
                probably be on, since you can disable it from the config
                file if you want to.  Defined by default in conf.h.
MIME8TO7        If non-zero, include 8 to 7 bit MIME conversions.  This
                also controls advertisement of 8BITMIME in the ESMTP
                startup dialogue.
MIME7TO8_OLD    If 0 then use an algorithm for MIME 7-bit quoted-printable
                or base64 encoding to 8-bit text that has been introduced
                in 8.12.3.  There are some examples where that code fails,
                but the old code works.  If you have an example of improper
                7 to 8 bit conversion please send it to sendmail-bugs.
MIME7TO8        If non-zero, include 7 to 8 bit MIME conversions.
HES_GETMAILHOST Define this to 1 if you are using Hesiod with the
                hes_getmailhost() routine.  This is included with the MIT
                Hesiod distribution, but not with the DEC Hesiod distribution.
XDEBUG          Do additional internal checking.  These don't cost too
                much; you might as well leave this on.
TCPWRAPPERS     Turns on support for the TCP wrappers library (-lwrap).
                See below for further information.
SECUREWARE      Enable calls to the SecureWare luid enabling/changing routines.
                SecureWare is a C2 security package added to several UNIX's
                (notably ConvexOS) to get a C2 Secure system.  This
                option causes mail delivery to be done with the luid of the
                recipient.
SHARE_V1        Support for the fair share scheduler, version 1.  Setting to
                1 causes final delivery to be done using the recipients
                resource limitations.  So far as I know, this is only
                supported on ConvexOS.
SASL            Enables SMTP AUTH (RFC 2554).  This requires the Cyrus SASL
                library (ftp://ftp.andrew.cmu.edu/pub/cyrus-mail/).  Please
                install at least version 1.5.13.  See below for further
                information: SASL COMPILATION AND CONFIGURATION.  If your
                SASL library is older than 1.5.10, you have to set this
                to its version number using a simple conversion:  a.b.c
                -> c + b*100 + a*10000, e.g. for 1.5.9 define SASL=10509.
                Note: Using an older version than 1.5.5 of Cyrus SASL is
                not supported.  Starting with version 1.5.10, setting SASL=1
                is sufficient.  Any value other than 1 (or 0) will be
                compared with the actual version found and if there is a
                mismatch, compilation will fail.
EGD             Define this if your system has EGD installed, see
                http://egd.sourceforge.net/ .  It should be used to
                seed the PRNG for STARTTLS if HASURANDOMDEV is not defined.
STARTTLS        Enables SMTP STARTTLS (RFC 2487).  This requires OpenSSL
                (http://www.OpenSSL.org/); use OpenSSL 0.9.8zc or later.
                See STARTTLS COMPILATION AND CONFIGURATION for further
                information.
TLS_EC          Enable use of elliptic curve cryptography in STARTTLS.
                If set to 2 sendmail uses SSL_CTX_set_ecdh_auto(),
                if set to 1 it selects the NID_X9_62_prime256v1 curve
                (created via EC_KEY_new_by_curve_name()) and uses
                SSL_CTX_set_tmp_ecdh().
                Support offered by different TLS libraries varies
                greatly: some old versions do not support elliptic curve
                cryptography at all, some new versions have it enabled
                by default (i.e., no need to set TLS_EC at all), while
                others may require one of the above settings.
TLS_NO_RSA      Turn off support for RSA algorithms in STARTTLS.
MILTER          Turn on support for external filters using the Milter API;
                this option is set by default, to turn it off use
                        APPENDDEF(`conf_sendmail_ENVDEF', `-DMILTER=0')
                in devtools/Site/site.config.m4 (see devtools/README).
                See libmilter/README for more information about milter.
REQUIRES_DIR_FSYNC      Turn on support for file systems that require to
                call fsync() for a directory if the meta-data in it has
                been changed.  This should be turned on at least for older
                versions of ReiserFS; it is enabled by default for Linux.
                According to some information this flag is not needed
                anymore for kernel 2.4.16 and newer.  We would appreciate
                feedback about the semantics of the various file systems
                available for Linux.
                An alternative to this compile time flag is to mount the
                queue directory without the -async option, or using
                chattr +S on Linux.
DBMMODE         The default file permissions to use when creating new
                database files for maps and aliases.  Defaults to 0640.
IPV6_FULL       Use uncompressed IPv6 addresses (set by default).  This
                permits a zero subnet to have a more specific match,
                such as different map entries for IPv6:0:0 vs IPv6:0.

Generic notice: If you enable a compile time option that needs
libraries or include files that don't come with sendmail or are
installed in a location that your C compiler doesn't use by default
you should set confINCDIRS and confLIBDIRS as explained in the
first section:  BUILDING SENDMAIL.


+---------------------+
| DNS/RESOLVER ISSUES |
+---------------------+

Many systems have old versions of the resolver library.  At a minimum,
you should be running BIND 4.8.3; older versions may compile, but they
have known bugs that should give you pause.

Common problems in old versions include "undefined" errors for
dn_skipname.

Some people have had a problem with BIND 4.9; it uses some routines
that it expects to be externally defined such as strerror().  It may
help to link with "-l44bsd" to solve this problem.  This has apparently
been fixed in later versions of BIND, starting around 4.9.3.  In other
words, if you use 4.9.0 through 4.9.2, you need -l44bsd; for earlier or
later versions, you do not.

!PLEASE! be sure to link with the same version of the resolver as
the header files you used -- some people have used the 4.9 headers
and linked with BIND 4.8 or vice versa, and it doesn't work.
Unfortunately, it doesn't fail in an obvious way -- things just
subtly don't work.

WILDCARD MX RECORDS ARE A BAD IDEA!  The only situation in which they
work reliably is if you have two versions of DNS, one in the real world
which has a wildcard pointing to your firewall, and a completely
different version of the database internally that does not include
wildcard MX records that match your domain.  ANYTHING ELSE WILL GIVE
YOU HEADACHES!

When attempting to canonify a hostname, some broken name servers will
return SERVFAIL (a temporary failure) on T_AAAA (IPv6) lookups.  If you
want to excuse this behavior, include WorkAroundBrokenAAAA in
ResolverOptions.  However, instead, we recommend catching the problem and
reporting it to the name server administrator so we can rid the world of
broken name servers.


+----------------------------------------+
| STARTTLS COMPILATION AND CONFIGURATION |
+----------------------------------------+

Please read the documentation accompanying the OpenSSL library.  You
have to compile and install the OpenSSL libraries before you can compile
sendmail.  See devtools/README how to set the correct compile time
parameters; you should at least set the following variables:

APPENDDEF(`conf_sendmail_ENVDEF', `-DSTARTTLS')
APPENDDEF(`conf_sendmail_LIBS', `-lssl -lcrypto')

If you have installed the OpenSSL libraries and include files in
a location that your C compiler doesn't use by default you should
set confINCDIRS and confLIBDIRS as explained in the first section:
BUILDING SENDMAIL.

Configuration information can be found in doc/op/op.me (required
certificates) and cf/README (how to tell sendmail about certificates).

To perform an initial test, connect to your sendmail daemon
(telnet localhost 25) and issue a EHLO localhost and see whether
250-STARTTLS
is in the response.  If it isn't, run the daemon with
-O LogLevel=14
and try again.  Then take a look at the logfile and see whether
there are any problems listed about permissions (unsafe files)
or the validity of X.509 certificates.

From: Garrett Wollman <wollman@lcs.mit.edu>

    If your certificate authority is hierarchical, and you only include
    the top-level CA certificate in the CACertFile file, some mail clients
    may be unable to infer the proper certificate chain when selecting a
    client certificate.  Including the bottom-level CA certificate(s) in
    the CACertFile file will allow these clients to work properly.  This
    is not necessary if you are not using client certificates for
    authentication, or if all your clients are running Sendmail or other
    programs using the OpenSSL library (which get it right automatically).
    In addition, some mail clients are totally incapable of using
    certificate authentication -- even some of those which already support
    SSL/TLS for confidentiality.

Further information can be found via:
http://www.sendmail.org/tips/


+------------------------------------+
| SASL COMPILATION AND CONFIGURATION |
+------------------------------------+

Please read the documentation accompanying the Cyrus SASL library
(INSTALL and README).  If you use Berkeley DB for Cyrus SASL then
you must compile sendmail with the same version of Berkeley DB.
See devtools/README for how to set the correct compile time parameters;
you should at least set the following variables:

APPENDDEF(`conf_sendmail_ENVDEF', `-DSASL')
APPENDDEF(`conf_sendmail_LIBS', `-lsasl')

If you have installed the Cyrus SASL library and include files in
a location that your C compiler doesn't use by default you should
set confINCDIRS and confLIBDIRS as explained in the first section:
BUILDING SENDMAIL.

You have to select and install authentication mechanisms and tell
sendmail where to find the sasl library and the include files (see
devtools/README for the parameters to set).  Set up the required
users and passwords as explained in the SASL documentation.  See
also cf/README for authentication related options (especially
DefaultAuthInfo if you want authentication between MTAs).

To perform an initial test, connect to your sendmail daemon
(telnet localhost 25) and issue a EHLO localhost and see whether
250-AUTH ....
is in the response.  If it isn't, run the daemon with
-O LogLevel=14
and try again.  Then take a look at the logfile and see whether
there are any security related problems listed (unsafe files).

Further information can be found via:
http://www.sendmail.org/tips/


+-------------------------------------+
| OPERATING SYSTEM AND COMPILE QUIRKS |
+-------------------------------------+

GCC problems
        When compiling with "gcc -O -Wall" specify "-DSM_OMIT_BOGUS_WARNINGS"
                too (see include/sm/cdefs.h for more info).

        *****************************************************************
        **  IMPORTANT:  DO NOT USE OPTIMIZATION (``-O'') IF YOU ARE    **
        **  RUNNING GCC 2.4.x or 2.5.x.  THERE IS A BUG IN THE GCC     **
        **  OPTIMIZER THAT CAUSES SENDMAIL COMPILES TO FAIL MISERABLY. **
        *****************************************************************

        Jim Wilson of Cygnus believes he has found the problem -- it will
        probably be fixed in GCC 2.5.6 -- but until this is verified, be
        very suspicious of gcc -O.  This problem is reported to have been
        fixed in gcc 2.6.

        A bug in gcc 2.5.5 caused problems compiling sendmail 8.6.5 with
        optimization on a Sparc.  If you are using gcc 2.5.5, youi should
        upgrade to the latest version of gcc.

        Apparently GCC 2.7.0 on the Pentium processor has optimization
        problems.  I recommend against using -O on that architecture.  This
        has been seen on FreeBSD 2.0.5 RELEASE.

        Solaris 2.X users should use version 2.7.2.3 over 2.7.2.

        We have been told there are problems with gcc 2.8.0.  If you are
        using this version, you should upgrade to 2.8.1 or later.

Berkeley DB
        Berkeley DB 4.1.x with x <= 24 does not work with sendmail.
        You need at least 4.1.25.

GDBM    GDBM does not work with sendmail because the additional
        security checks and file locking cause problems.  Unfortunately,
        gdbm does not provide a compile flag in its version of ndbm.h so
        the code can adapt.  Until the GDBM authors can fix these problems,
        GDBM will not be supported.  Please use Berkeley DB instead.

Configuration file location
        Up to 8.6, sendmail tried to find the sendmail.cf file in the same
        place as the vendors had put it, even when this was obviously
        stupid.  As of 8.7, sendmail ALWAYS looks for /etc/sendmail.cf.
        Beginning with 8.10, sendmail uses /etc/mail/sendmail.cf.
        You can get sendmail to use the stupid vendor .cf location by
        adding -DUSE_VENDOR_CF_PATH during compilation, but this may break
        support programs and scripts that need to find sendmail.cf.  You
        are STRONGLY urged to use symbolic links if you want to use the
        vendor location rather than changing the location in the sendmail
        binary.

        NETINFO systems use NETINFO to determine the location of
        sendmail.cf.  The full path to sendmail.cf is stored as the value of
        the "sendmail.cf" property in the "/locations/sendmail"
        subdirectory of NETINFO.  Set the value of this property to
        "/etc/mail/sendmail.cf" (without the quotes) to use this new
        default location for Sendmail 8.10.0 and higher.

ControlSocket permissions
        Paraphrased from BIND 8.2.1's README:

        Solaris and other pre-4.4BSD kernels do not respect ownership or
        protections on UNIX-domain sockets.  The short term fix for this is to
        override the default path and put such control sockets into root-
        owned directories which do not permit non-root to r/w/x through them.
        The long term fix is for all kernels to upgrade to 4.4BSD semantics.

HP MPE/iX
        The MPE-specific code within sendmail emulates a set-user-id root
        environment for the sendmail binary.  But there is no root uid 0 on
        MPE, nor is there any support for set-user-id programs.  Even when
        sendmail thinks it is running as uid 0, it will still have the file
        access rights of the underlying non-zero uid, but because sendmail is
        an MPE priv-mode program it will still be able to call setuid() to
        successfully switch to a new uid.

        MPE setgid() semantics don't quite work the way sendmail expects, so
        special emulation is done here also.

        This uid/gid emulation is enabled via the setuid/setgid file mode bits
        which are not currently used by MPE.  Code in libsm/mpeix.c examines
        these bits and enables emulation if they have been set, i.e.,
        chmod u+s,g+s /SENDMAIL/CURRENT/SENDMAIL.

SunOS 4.x (Solaris 1.x)
        You may have to use -lresolv on SunOS.  However, beware that
        this links in a new version of gethostbyname that does not
        understand NIS, so you must have all of your hosts in DNS.

        Some people have reported problems with the SunOS version of
        -lresolv and/or in.named, and suggest that you get a newer
        version.  The symptoms are delays when you connect to the
        SMTP server on a SunOS machine or having your domain added to
        addresses inappropriately.  There is a version of BIND
        version 4.9 on gatekeeper.DEC.COM in pub/BSD/bind/4.9.

        There is substantial disagreement about whether you can make
        this work with resolv+, which allows you to specify a search-path
        of services.  Some people report that it works fine, others
        claim it doesn't work at all (including causing sendmail to
        drop core when it tries to do multiple resolv+ lookups for a
        single job).  I haven't tried resolv+, as we use DNS exclusively.

        Should you want to try resolv+, it is on ftp.uu.net in
        /networking/ip/dns.

        Apparently getservbyname() can fail under moderate to high
        load under some circumstances.  This will exhibit itself as
        the message ``554 makeconnection: service "smtp" unknown''.
        The problem has been traced to one or more blank lines in
        /etc/services on the NIS server machine.  Delete these
        and it should work.  This info is thanks to Brian Bartholomew
        <bb@math.ufl.edu> of I-Kinetics, Inc.

        NOTE: The SunOS 4.X linker uses library paths specified during
        compilation using -L for run-time shared library searches.
        Therefore, it is vital that relative and unsafe directory paths not
        be used when compiling sendmail.

SunOS 4.0.2 (Sun 386i)
        Date: Fri, 25 Aug 1995 11:13:58 +0200 (MET DST)
        From: teus@oce.nl

        Sendmail 8.7.Beta.12 compiles and runs nearly out of the box with the
        following changes:
        * Don't use /usr/5bin in your PATH, but make /usr/5bin/uname
          available as "uname" command.
        * Use the defines "-DBSD4_3 -DNAMED_BIND=0" in
          devtools/OS/SunOS.4.0, which is selected via the "uname" command.
        I recommend to make available the db-library on the system first
        (and change the Makefile to use this library).
        Note that the sendmail.cf and aliases files are found in /etc.

SunOS 4.1.3, 4.1.3_U1
        Sendmail causes crashes on SunOS 4.1.3 and 4.1.3_U1.  According
        to Sun bug number 1077939:

        If an application does a getsockopt() on a SOCK_STREAM (TCP) socket
        after the other side of the connection has sent a TCP RESET for
        the stream, the kernel gets a Bus Trap in the tcp_ctloutput() or
        ip_ctloutput() routine.

        For 4.1.3, this is fixed in patch 100584-08, available on the
        Sunsolve 2.7.1 or later CDs.  For 4.1.3_U1, this was fixed in patch
        101790-01 (SunOS 4.1.3_U1: TCP socket and reset problems), later
        obsoleted by patch 102010-05.

        Sun patch 100584-08 is not currently publicly available on their
        ftp site but a user has reported it can be found at other sites
        using a web search engine.

Solaris 2.x (SunOS 5.x)
        To compile for Solaris, the Makefile built by Build must
        include a SOLARIS definition which reflects the Solaris version
        (i.e. -DSOLARIS=20400 for 2.4 or -DSOLARIS=20501 for 2.5.1).
        If you are using gcc, make sure -I/usr/include is not used (or
        it might complain about TopFrame).  If you are using Sun's cc,
        make sure /opt/SUNWspro/bin/cc is used instead of /usr/ucb/cc
        (or it might complain about tm_zone).

        The Solaris 2.x (x <= 3) "syslog" function is apparently limited
        to something about 90 characters because of a kernel limitation.
        If you have source code, you can probably up this number.  You
        can get patches that fix this problem:  the patch ids are:

                Solaris 2.1     100834
                Solaris 2.2     100999
                Solaris 2.3     101318

        Be sure you have the appropriate patch installed or you won't
        see system logging.

Solaris 2.4 (SunOS 5.4)
        If you include /usr/lib at the end of your LD_LIBRARY_PATH you run
        the risk of getting the wrong libraries under some circumstances.
        This is because of a new feature in Solaris 2.4, described by
        Rod.Evans@Eng.Sun.COM:

        >> Prior to SunOS 5.4, any LD_LIBRARY_PATH setting was ignored by the
        >> runtime linker if the application was setxid (secure), thus your
        >> applications search path would be:
        >>
        >>      /usr/local/lib  LD_LIBRARY_PATH component - IGNORED
        >>      /usr/lib        LD_LIBRARY_PATH component - IGNORED
        >>      /usr/local/lib  RPATH - honored
        >>      /usr/lib        RPATH - honored
        >>
        >> the effect is that path 3 would be the first used, and this would
        >> satisfy your resolv.so lookup.
        >>
        >> In SunOS 5.4 we made the LD_LIBRARY_PATH a little more flexible.
        >> People who developed setxid applications wanted to be able to alter
        >> the library search path to some degree to allow for their own
        >> testing and debugging mechanisms.  It was decided that the only
        >> secure way to do this was to allow a `trusted' path to be used in
        >> LD_LIBRARY_PATH.  The only trusted directory we presently define
        >> is /usr/lib.  Thus a set-user-ID root developer could play with some
        >> alternative shared object implementations and place them in
        >> /usr/lib (being root we assume they'ed have access to write in this
        >> directory).  This change was made as part of 1155380 - after a
        >> *huge* amount of discussion regarding the security aspect of things.
        >>
        >> So, in SunOS 5.4 your applications search path would be:
        >>
        >>      /usr/local/lib  from LD_LIBRARY_PATH - IGNORED (untrustworthy)
        >>      /usr/lib        from LD_LIBRARY_PATH - honored (trustworthy)
        >>      /usr/local/lib  from RPATH - honored
        >>      /usr/lib        from RPATH - honored
        >>
        >> here, path 2 would be the first used.

Solaris 2.5.1 (SunOS 5.5.1) and 2.6 (SunOS 5.6)
        Apparently Solaris 2.5.1 patch 103663-01 installs a new
        /usr/include/resolv.h file that defines the __P macro without
        checking to see if it is already defined.  This new resolv.h is also
        included in the Solaris 2.6 distribution.  This causes compile
        warnings such as:

           In file included from daemon.c:51:
           /usr/include/resolv.h:208: warning: `__P' redefined
           cdefs.h:58: warning: this is the location of the previous definition

        These warnings can be safely ignored or you can create a resolv.h
        file in the obj.SunOS.5.5.1.* or obj.SunOS.5.6.* directory that reads:

           #undef __P
           #include "/usr/include/resolv.h"

        This problem was fixed in Solaris 7 (Sun bug ID 4081053).

Solaris 7 (SunOS 5.7)
        Solaris 7 includes LDAP libraries but the implementation was
        lacking a few things.  The following settings can be placed in
        devtools/Site/site.SunOS.5.7.m4 if you plan on using those
        libraries.

        APPENDDEF(`confMAPDEF', `-DLDAPMAP')
        APPENDDEF(`confENVDEF', `-DLDAP_VERSION_MAX=3')
        APPENDDEF(`confLIBS', `-lldap')

        Also, Sun's patch 107555 is needed to prevent a crash in the call
        to ldap_set_option for LDAP_OPT_REFERRALS in ldapmap_setopts if
        LDAP support is compiled in sendmail.

Solaris 8 and later (SunOS 5.8 and later)
        Solaris 8 and later can optionally install LDAP support.  If you
        have installed the Entire Distribution meta-cluster, you can use
        the following in devtools/Site/site.SunOS.5.8.m4 (or other
        appropriately versioned file) to enable LDAP:

        APPENDDEF(`confMAPDEF', `-DLDAPMAP')
        APPENDDEF(`confLIBS', `-lldap')

Solaris 9 and later (SunOS 5.9 and later)
        Solaris 9 and later have a revised LDAP library, libldap.so.5,
        which is derived from a Netscape implementation, thus requiring
        that SM_CONF_LDAP_MEMFREE be defined in conjunction with LDAPMAP:

        APPENDDEF(`confMAPDEF', `-DLDAPMAP')
        APPENDDEF(`confENVDEF', `-DSM_CONF_LDAP_MEMFREE')
        APPENDDEF(`confLIBS', `-lldap')

Solaris
        If you are using dns for hostname resolution on Solaris, make sure
        that the 'dns' entry is last on the hosts line in
        '/etc/nsswitch.conf'.  For example, use:

                hosts:  nisplus files dns

        Do not use:

                hosts:  nisplus dns [NOTFOUND=return] files

        Note that 'nisplus' above is an illustration.  The same comment
        applies no matter what naming services you are using.  If you have
        anything other than dns last, even after "[NOTFOUND=return]",
        sendmail may not be able to determine whether an error was
        temporary or permanent.  The error returned by the solaris
        gethostbyname() is the error for the last lookup used, and other
        naming services do not have the same concept of temporary failure.

Ultrix
        By default, the IDENT protocol is turned off on Ultrix.  If you
        are running Ultrix 4.4 or later, or if you have included patch
        CXO-8919 for Ultrix 4.2 or 4.3 to fix the TCP problem, you can turn
        IDENT on in the configuration file by setting the "ident" timeout.

        The Ultrix 4.5 Y2K patch (ULTV45-022-1) has changed the resolver
        included in libc.a.  Unfortunately, the __RES symbol hasn't changed
        and therefore, sendmail can no longer automatically detect the
        newer version.  If you get a compiler error:

        /lib/libc.a(gethostent.o): local_hostname_length: multiply defined

        Then rebuild with this in devtools/Site/site.ULTRIX.m4:

        APPENDDEF(`conf_sendmail_ENVDEF', `-DNEEDLOCAL_HOSTNAME_LENGTH=0')

Digital UNIX (formerly DEC OSF/1)
        If you are compiling on OSF/1 (DEC Alpha), you must use
        -L/usr/shlib (otherwise it core dumps on startup).  You may also
        need -mld to get the nlist() function, although some versions
        apparently don't need this.

        Also, the enclosed makefile removed /usr/sbin/smtpd; if you need
        it, just create the link to the sendmail binary.

        On DEC OSF/1 3.2 or earlier, the MatchGECOS option doesn't work
        properly due to a bug in the getpw* routines.  If you want to use
        this, use -DDEC_OSF_BROKEN_GETPWENT=1.  The problem is fixed in 3.2C.

        Digital's mail delivery agent, /bin/mail (aka /bin/binmail), will
        only preserve the envelope sender in the "From " header if
        DefaultUserID is set to daemon.  Setting this to mailnull will
        cause all mail to have the header "From mailnull ...".  To use
        a different DefaultUserID, you will need to use a different mail
        delivery agent (such as mail.local found in the sendmail
        distribution).

        On Digital UNIX 4.0 and later, Berkeley DB 1.85 is included with the
        operating system and already has the ndbm.o module removed.  However,
        Digital has modified the original Berkeley DB db.h include file.
        This results in the following warning while compiling map.c and udb.c:

        cc: Warning: /usr/include/db.h, line 74: The redefinition of the macro
         "__signed" conflicts with a current definition because the replacement
         lists differ.  The redefinition is now in effect.
        #define __signed        signed
        ------------------------^

        This warning can be ignored.

        Digital UNIX's linker checks /usr/ccs/lib/ before /usr/lib/.
        If you have installed a new version of BIND in /usr/include
        and /usr/lib, you will experience difficulties as Digital ships
        libresolv.a in /usr/ccs/lib/ as well.  Be sure to replace both
        copies of libresolv.a.

IRIX
        The header files on SGI IRIX are completely prototyped, and as
        a result you can sometimes get some warning messages during
        compilation.  These can be ignored.  There are two errors in
        deliver only if you are using gcc, both of the form ``warning:
        passing arg N of `execve' from incompatible pointer type''.
        Also, if you compile with -DNIS, you will get a complaint
        about a declaration of struct dom_binding in a prototype
        when compiling map.c; this is not important because the
        function being prototyped is not used in that file.

        In order to compile sendmail you will have had to install
        the developers' option in order to get the necessary include
        files.

        If you compile with -lmalloc (the fast memory allocator), you may
        get warning messages such as the following:

           ld32: WARNING 85: definition of _calloc in /usr/lib32/libmalloc.so
                preempts that definition in /usr/lib32/mips3/libc.so.
           ld32: WARNING 85: definition of _malloc in /usr/lib32/libmalloc.so
                preempts that definition in /usr/lib32/mips3/libc.so.
           ld32: WARNING 85: definition of _realloc in /usr/lib32/libmalloc.so
                preempts that definition in /usr/lib32/mips3/libc.so.
           ld32: WARNING 85: definition of _free in /usr/lib32/libmalloc.so
                preempts that definition in /usr/lib32/mips3/libc.so.
           ld32: WARNING 85: definition of _cfree in /usr/lib32/libmalloc.so
                preempts that definition in /usr/lib32/mips3/libc.so.

        These are unavoidable and innocuous -- just ignore them.

        According to Dave Sill <de5@ornl.gov>, there is a version of the
        Berkeley DB library patched to run on Irix 6.2 available from
        http://reality.sgi.com/ariel/freeware/#db .

IRIX 6.x
        If you are using XFS filesystem, avoid using the -32 ABI switch to
        the cc compiler if possible.

        Broken inet_aton and inet_ntoa on IRIX using gcc: There's
        a problem with gcc on IRIX, i.e., gcc can't pass structs
        less than 16 bits long unless they are 8 bits; IRIX 6.2 has
        some other sized structs.  See
        http://www.bitmechanic.com/mail-archives/mysql/current/0418.html
        This problem seems to be fixed by gcc v2.95.2, gcc v2.8.1
        is reported as broken.  Check your gcc version for this bug
        before installing sendmail.

IRIX 6.4
        The IRIX 6.5.4 version of /bin/m4 does not work properly with
        sendmail.  Either install fw_m4.sw.m4 off the Freeware_May99 CD and
        use /usr/freeware/bin/m4 or install and use GNU m4.

NeXT or NEXTSTEP
        NEXTSTEP 3.3 and earlier ship with the old DBM library.  Also,
        Berkeley DB does not currently run on NEXTSTEP.

        If you are compiling on NEXTSTEP, you will have to create an
        empty file "unistd.h" and create a file "dirent.h" containing:

                #include <sys/dir.h>
                #define dirent  direct

        (devtools/OS/NeXT should try to do both of these for you.)

        Apparently, there is a bug in getservbyname on Nextstep 3.0
        that causes it to fail under some circumstances with the
        message "SYSERR: service "smtp" unknown" logged.  You should
        be able to work around this by including the line:

                OOPort=25

        in your .cf file.

BSDI (BSD/386) 1.0, NetBSD 0.9, FreeBSD 1.0
        The "m4" from BSDI won't handle the config files properly.
        I haven't had a chance to test this myself.

        The M4 shipped in FreeBSD and NetBSD 0.9 don't handle the config
        files properly.  One must use either GNU m4 1.1 or the PD-M4
        recently posted in comp.os.386bsd.bugs (and maybe others).
        NetBSD-current includes the PD-M4 (as stated in the NetBSD file
        CHANGES).

        FreeBSD 1.0 RELEASE has uname(2) now.  Use -DUSEUNAME in order to
        use it (look into devtools/OS/FreeBSD).  NetBSD-current may have
        it too but it has not been verified.

        The latest version of Berkeley DB uses a different naming
        scheme than the version that is supplied with your release.  This
        means you will be able to use the current version of Berkeley DB
        with sendmail as long you use the new db.h when compiling
        sendmail and link it against the new libdb.a or libdb.so.  You
        should probably keep the original db.h in /usr/include and the
        new db.h in /usr/local/include.

4.3BSD
        If you are running a "virgin" version of 4.3BSD, you'll have
        a very old resolver and be missing some header files.  The
        header files are simple -- create empty versions and everything
        will work fine.  For the resolver you should really port a new
        version (4.8.3 or later) of the resolver; 4.9 is available on
        gatekeeper.DEC.COM in pub/BSD/bind/4.9.  If you are really
        determined to continue to use your old, buggy version (or as
        a shortcut to get sendmail working -- I'm sure you have the
        best intentions to port a modern version of BIND), you can
        copy ../contrib/oldbind.compat.c into sendmail and add the
        following to devtools/Site/site.config.m4:

        APPENDDEF(`confOBJADD', `oldbind.compat.o')

OpenBSD (up to 2.9 Release), NetBSD, FreeBSD (up to 4.3-RELEASE)
        m4 from *BSD won't handle libsm/Makefile.m4 properly, since the
        maximum length for strings is too short.  You need to use GNU m4
        or patch m4, see for example:
  http://FreeBSD.org/cgi/cvsweb.cgi/src/usr.bin/m4/eval.c.diff?r1=1.11&r2=1.12

A/UX
        Date: Tue, 12 Oct 1993 18:28:28 -0400 (EDT)
        From: "Eric C. Hagberg" <hagberg@med.cornell.edu>
        Subject: Fix for A/UX ndbm

        I guess this isn't really a sendmail bug, however, it is something
        that A/UX users should be aware of when compiling sendmail 8.6.

        Apparently, the calls that sendmail is using to the ndbm routines
        in A/UX 3.0.x contain calls to "broken" routines, in that the
        aliases database will break when it gets "just a little big"
        (sorry I don't have exact numbers here, but it broke somewhere
        around 20-25 aliases for me.), making all aliases non-functional
        after exceeding this point.

        What I did was to get the gnu-dbm-1.6 package, compile it, and
        then re-compile sendmail with "-lgdbm", "-DNDBM", and using the
        ndbm.h header file that comes with the gnu-package.  This makes
        things behave properly.
          [NOTE: see comment above about GDBM]

        I suppose porting the New Berkeley DB package is another route,
        however, I made a quick attempt at it, and found it difficult
        (not easy at least); the gnu-dbm package "configured" and
        compiled easily.

          [NOTE: Berkeley DB version 2.X runs on A/UX and can be used for
          database maps.]

SCO Unix
        From: Thomas Essebier <tom@stallion.oz.au>
        Organisation:  Stallion Technologies Pty Ltd.

        It will probably help those who are trying to configure sendmail 8.6.9
        to know that if they are on SCO, they had better set
                OI-dnsrch
        or they will core dump as soon as they try to use the resolver.
        i.e., although SCO has _res.dnsrch defined, and is kinda BIND 4.8.3,
        it does not inititialise it, nor does it understand 'search' in
        /etc/named.boot.
                - sigh -

        According to SCO, the m4 which ships with UnixWare 2.1.2 is broken.
        We recommend installing GNU m4 before attempting to build sendmail.

        On some versions a bogus error value is listed if connections
        time out (large negative number).  To avoid this explicitly set
        Timeout.connect to a reasonable value (several minutes).

DG/UX
        Doug Anderson <dlander@afterlife.ncsc.mil> has successfully run
        V8 on the DG/UX 5.4.2 and 5.4R3.x platforms under heavy usage.
        Originally, the DG /bin/mail program wasn't compatible with
        the V8 sendmail, since the DG /bin/mail requires the environment
        variable "_FORCE_MAIL_LOCAL_=yes" be set.  Version 8.7 now includes
        this in the environment before invoking the local mailer.  Some
        have used procmail to avoid this problem in the past.  It works
        but some have experienced file locking problems with their DG/UX
        ports of procmail.

Apollo DomainOS
        If you are compiling on Apollo, you will have to create an empty
        file "unistd.h" (for DomainOS 10.3 and earlier) and create a file
        "dirent.h" containing:

                #include <sys/dir.h>
                #define dirent  direct

        (devtools/OS/DomainOS will attempt to do both of these for you.)

HP-UX 8.00
        Date: Mon, 24 Jan 1994 13:25:45 +0200
        From: Kimmo Suominen <Kimmo.Suominen@lut.fi>
        Subject: 8.6.5 w/ HP-UX 8.00 on s300

        Just compiled and fought with sendmail 8.6.5 on a HP9000/360 (i.e.,
        a series 300 machine) running HP-UX 8.00.

        I was getting segmentation fault when delivering to a local user.
        With debugging I saw it was faulting when doing _free@libc... *sigh*
        It seems the new implementation of malloc on s300 is buggy as of 8.0,
        so I tried out the one in -lmalloc (malloc(3X)).  With that it seems
        to work just dandy.

        When linking, you will get the following error:

        ld: multiply defined symbol _freespace in file /usr/lib/libmalloc.a

        but you can just ignore it.  You might want to add this info to the
        README file for the future...

Linux
        Something broke between versions 0.99.13 and 0.99.14 of Linux: the
        flock() system call gives errors.  If you are running .14, you must
        not use flock.  You can do this with -DHASFLOCK=0.  We have also
        been getting complaints since version 2.4.X was released.
        sendmail 8.13 has changed the default locking method to fcntl()
        for Linux kernel version 2.4 and later.  Be sure to update other
        sendmail related programs to match locking techniques (some
        examples, besides makemap and mail.local, include procmail, mailx,
        mutt, elm, etc).

        Around the inclusion of bind-4.9.3 & Linux libc-4.6.20, the
        initialization of the _res structure changed.  If /etc/hosts.conf
        was configured as "hosts, bind" the resolver code could return
        "Name server failure" errors.  This is supposedly fixed in
        later versions of libc (>= 4.6.29?), and later versions of
        sendmail (> 8.6.10) try to work around the problem.

        Some older versions (< 4.6.20?) of the libc/include files conflict
        with sendmail's version of cdefs.h.  Deleting sendmail's version
        on those systems should be non-harmful, and new versions don't care.

        NOTE ON LINUX & BIND:  By default, the Makefile generated for Linux
        includes header files in /usr/local/include and libraries in
        /usr/local/lib.  If you've installed BIND on your system, the header
        files typically end up in the search path and you need to add
        "-lresolv" to the LIBS line in your Makefile.  Really old versions
        may need to include "-l44bsd" as well (particularly if the link phase
        complains about missing strcasecmp, strncasecmp or strpbrk).
        Complaints about an undefined reference to `__dn_skipname' in
        domain.o are a sure sign that you need to add -lresolv to LIBS.
        Newer versions of Linux are basically threaded BIND, so you may or
        may not see complaints if you accidentally mix BIND
        headers/libraries with virginal libc.  If you have BIND headers in
        /usr/local/include (resolv.h, etc) you *should* be adding -lresolv
        to LIBS.  Data structures may change and you'd be asking for a
        core dump.

        A number of problems have been reported regarding the Linux 2.2.0
        kernel.  So far, these problems have been tracked down to syslog()
        and DNS resolution.  We believe the problem is with the poll()
        implementation in the Linux 2.2.0 kernel and poll()-aware versions
        of glib (at least up to 2.0.111).

glibc
        glibc 2.2.1 (and possibly other versions) changed the value of
        __RES in resolv.h but failed to actually provide the IPv6 API
        changes that the change implied.  Therefore, compiling with
        -DNETINET6 fails.

        Workarounds:
        1) Compile without -DNETINET6
        2) Build against a real BIND 8.2.2 include/lib tree
        3) Wait for glibc to fix it

AIX 4.X
        The AIX 4.X linker uses library paths specified during compilation
        using -L for run-time shared library searches.  Therefore, it is
        vital that relative and unsafe directory paths not be using when
        compiling sendmail.  Because of this danger, by default, compiles
        on AIX use the -blibpath option to limit shared libraries to
        /usr/lib and /lib.  If you need to allow more directories, such as
        /usr/local/lib, modify your devtools/Site/site.AIX.4.2.m4,
        site.AIX.4.3.m4, and/or site.AIX.4.x.m4 file(s) and set confLDOPTS
        appropriately.  For example:

        define(`confLDOPTS', `-blibpath:/usr/lib:/lib:/usr/local/lib')

        Be sure to only add (safe) system directories.

        The AIX version of GNU ld also exhibits this problem.  If you are
        using that version, instead of -blibpath, use its -rpath option.
        For example:

        gcc -Wl,-rpath /usr/lib -Wl,-rpath /lib -Wl,-rpath /usr/local/lib

AIX 4.X If the test program t-event (and most others) in libsm fails,
        check your compiler settings.  It seems that the flags -qnoro or
        -qnoroconst on some AIX versions trigger a compiler bug.  Check
        your compiler settings or use cc instead of xlc.

AIX 4.0-4.2, maybe some AIX 4.3 versions
        The AIX m4 implements a different mechanism for ifdef which is
        inconsistent with other versions of m4.  Therefore, it will not
        work properly with the sendmail Build architecture or m4
        configuration method.  To work around this problem, please use
        GNU m4 from ftp://ftp.gnu.org/pub/gnu/.
        The problem seems to be solved in AIX 4.3.3 at least.

AIX 4.3.3
        From: Valdis.Kletnieks@vt.edu
        Date: Sun, 02 Jul 2000 03:58:02 -0400

        Under AIX 4.3.3, after applying bos.adt.include 4.3.3.12 to close the
        BIND 8.2.2 security holes, you can no longer build with  -DNETINET6
        because they changed the value of __RES in resolv.h but failed to
        actually provide the API changes that the change implied.

        Workarounds:
        1) Compile without -DNETINET6
        2) Build against a real BIND 8.2.2 include/lib tree
        3) Wait for IBM to fix it

AIX 3.x
        This version of sendmail does not support MB, MG, and MR resource
        records, which are supported by AIX sendmail.

        Several people have reported that the IBM-supplied named returns
        fairly random results -- the named should be replaced.  It is not
        necessary to replace the resolver, which will simplify installation.
        A new BIND resolver can be found at http://www.isc.org/isc/.

AIX 3.1.x
        The supplied load average code only works correctly for AIX 3.2.x.
        For 3.1, use -DLA_TYPE=LA_SUBR and get the latest ``monitor''
        package by Jussi Maki <jmaki@hut.fi> from ftp.funet.fi in the
        directory pub/unix/AIX/rs6000/monitor-1.12.tar.Z; use the loadavgd
        daemon, and the getloadavg subroutine supplied with that package.
        If you don't care about load average throttling, just turn off
        load average checking using -DLA_TYPE=LA_ZERO.

RISC/os
        RISC/os from MIPS is a merged AT&T/Berkeley system.  When you
        compile on that platform you will get duplicate definitions
        on many files.  You can ignore these.

System V Release 4 Based Systems
        There is a single devtools OS that is intended for all SVR4-based
        systems (built from devtools/OS/SVR4).  It defines __svr4__,
        which is predefined by some compilers.  If your compiler already
        defines this compile variable, you can delete the definition from
        the generated Makefile or create a devtools/Site/site.config.m4
        file.

        It's been tested on Dell Issue 2.2.

DELL SVR4
        Date:      Mon, 06 Dec 1993 10:42:29 EST
        From: "Kimmo Suominen" <kim@grendel.lut.fi>
        Message-ID: <2d0352f9.lento29@lento29.UUCP>
        To: eric@cs.berkeley.edu
        Cc: sendmail@cs.berkeley.edu
        Subject:   Notes for DELL SVR4

        Eric,

        Here are some notes for compiling Sendmail 8.6.4 on DELL SVR4.  I ran
        across these things when helping out some people who contacted me by
        e-mail.

        1) Use gcc 2.4.5 (or later?).  Dell distributes gcc 2.1 with their
           Issue 2.2 Unix.  It is too old, and gives you problems with
           clock.c, because sigset_t won't get defined in <sys/signal.h>.
           This is due to a problematic protection rule in there, and is
           fixed with gcc 2.4.5.

        2) If you don't use the new Berkeley DB (-DNEWDB), then you need
           to add "-lc -lucb" to the libraries to link with.  This is because
           the -ldbm distributed by Dell needs the bcopy, bcmp and bzero
           functions.  It is important that you specify both libraries in
           the given order to be sure you only get the BSTRING functions
           from the UCB library (and not the signal routines etc.).

        3) Don't leave out "-lelf" even if compiling with "-lc -lucb".
           The UCB library also has another copy of the nlist routines,
           but we do want the ones from "-lelf".

        If anyone needs a compiled gcc 2.4.5 and/or a ported DB library, they
        can use anonymous ftp to fetch them from lut.fi in the /kim directory.
        They are copies of what I use on grendel.lut.fi, and offering them
        does not imply that I would also support them.  I have sent the DB
        port for SVR4 back to Keith Bostic for inclusion in the official
        distribution, but I haven't heard anything from him as of today.

        - gcc-2.4.5-svr4.tar.gz (gcc 2.4.5 and the corresponding libg++)
        - db-1.72.tar.gz        (with source, objects and a installed copy)

        Cheers
        + Kim
        --
         *  Kimmo.Suominen@lut.fi  *  SysVr4 enthusiast at GRENDEL.LUT.FI  *
        *    KIM@FINFILES.BITNET   *  Postmaster and Hostmaster at LUT.FI   *
         *    + 358 200 865 718    *  Unix area moderator at NIC.FUNET.FI  *

ConvexOS 10.1 and below
        In order to use the name server, you must create the file
        /etc/use_nameserver.  If this file does not exist, the call
        to res_init() will fail and you will have absolutely no
        access to DNS, including MX records.

Amdahl UTS 2.1.5
        In order to get UTS to work, you will have to port BIND 4.9.
        The vendor's BIND is reported to be ``totally inadequate.''
        See sendmail/contrib/AmdahlUTS.patch for the patches necessary
        to get BIND 4.9 compiled for UTS.

UnixWare
        According to Alexander Kolbasov <sasha@unitech.gamma.ru>,
        the m4 on UnixWare 2.0 (still in Beta) will core dump on the
        config files.  GNU m4 and the m4 from UnixWare 1.x both work.

        According to Larry Rosenman <ler@lerami.lerctr.org>:

                UnixWare 2.1.[23]'s m4 chokes (not obviously) when
                processing the 8.9.0 cf files.

                I had a LOCAL_RULE_0 that wound up AFTER the
                SBasic_check_rcpt rules using the SCO supplied M4.
                GNU M4 works fine.

UNICOS 8.0.3.4
        Some people have reported that the -O flag on UNICOS can cause
        problems.  You may want to turn this off if you have problems
        running sendmail.  Reported by Jerry G. DeLapp <jgd@acl.lanl.gov>.

Darwin/Mac OS X (10.X.X)
        The linker errors produced regarding getopt() and its associated
        variables can safely be ignored.

        From Mike Zimmerman <zimmy@torrentnet.com>:

        From scratch here is what Darwin users need to do to the standard
        10.0.0, 10.0.1 install to get sendmail working.
        From http://www.macosx.com/forums/showthread.php?s=6dac0e9e1f3fd118a4870a8a9b559491&threadid=2242:
        1. chmod g-w / /private /private/etc
        2. Properly set HOSTNAME in /etc/hostconfig to your FQDN:
           HOSTNAME=-my.domain.com-
        3. Edit /etc/rc.boot:
           hostname my.domain.com
           domainname domain.com
        4. Edit /System/Library/StartupItems/Sendmail/Sendmail:
           Remove the "&" after the sendmail command:
           /usr/sbin/sendmail -bd -q1h

        From Carsten Klapp <carsten.klapp@home.com>:

        The easiest workaround is to remove the group-writable permission
        for the root directory and the symbolic /etc inherits this
        change. While this does fix sendmail, the unfortunate side-effect
        is the OS X admin will no longer be able to manipulate icons in the
        top level of the Startup disk unless logged into the GUI as the
        superuser.

        In applying the alternate workaround, care must be taken while
        swapping the symlink /etc with the directory /private/etc. In all
        likelihood any admin who is concerned with this sendmail error has
        enough experience to not accidentally harm anything in the process.

        a. Swap the /etc symlink with /private/etc (as superuser):
           rm /etc
           mv /private/etc /etc
           ln -s /etc /private/etc

        b. Set / to group unwritable (as superuser):
           chmod g-w /

Darwin/Mac OS X (10.1.5)
        Apple's upgrade to sendmail 8.12 is incorrectly configured.  You
        will need to manually fix it up by doing the following:

        1. chown smmsp:smmsp /var/spool/clientmqueue
        2. chmod 2770 /var/spool/clientmqueue
        3. chgrp smmsp /usr/sbin/sendmail
        4. chmod g+s /usr/sbin/sendmail

        From Daniel J. Luke <dluke@geeklair.net>:

        It appears that setting the sendmail.cf property in
        /locations/sendmail in NetInfo on Mac OS X 10.1.5 with sendmail
        8.12.4 causes 'bad things' to happen.

        Specifically sendmail instances that should be getting their config
        from /etc/mail/submit.cf don't (so mail/mutt/perl scripts which
        open pipes to sendmail stop working as sendmail tries to write to
        /var/spool/mqueue and cannot as sendmail is no longer suid root).

        Removing the entry from NetInfo fixes this problem.

GNU getopt
        I'm told that GNU getopt has a problem in that it gets confused
        by the double call.  Use the version in conf.c instead.

BIND 4.9.2 and Ultrix
        If you are running on Ultrix, be sure you read conf/Info.Ultrix
        in the BIND distribution very carefully -- there is information
        in there that you need to know in order to avoid errors of the
        form:

                /lib/libc.a(gethostent.o): sethostent: multiply defined
                /lib/libc.a(gethostent.o): endhostent: multiply defined
                /lib/libc.a(gethostent.o): gethostbyname: multiply defined
                /lib/libc.a(gethostent.o): gethostbyaddr: multiply defined

        during the link stage.

BIND 8.X
        BIND 8.X returns HOST_NOT_FOUND instead of TRY_AGAIN on temporary
        DNS failures when trying to find the hostname associated with an IP
        address (gethostbyaddr()).  This can cause problems as
        $&{client_name} based lookups in class R ($=R) and the access
        database won't succeed.

        This will be fixed in BIND 8.2.1.  For earlier versions, this can
        be fixed by making "dns" the last name service queried for host
        resolution in /etc/irs.conf:

                hosts local continue
                hosts dns

strtoul
        Some compilers (notably gcc) claim to be ANSI C but do not
        include the ANSI-required routine "strtoul".  If your compiler
        has this problem, you will get an error in srvrsmtp.c on the
        code:

          # ifdef defined(__STDC__) && !defined(BROKEN_ANSI_LIBRARY)
                        e->e_msgsize = strtoul(vp, (char **) NULL, 10);
          # else
                        e->e_msgsize = strtol(vp, (char **) NULL, 10);
          # endif

        You can use -DBROKEN_ANSI_LIBRARY to get around this problem.

Listproc 6.0c
        Date: 23 Sep 1995 23:56:07 GMT
        Message-ID: <95925101334.~INN-AUMa00187.comp-news@dl.ac.uk>
        From: alansz@mellers1.psych.berkeley.edu (Alan Schwartz)
        Subject: Listproc 6.0c + Sendmail 8.7 [Helpful hint]

        Just upgraded to sendmail 8.7, and discovered that listproc 6.0c
        breaks, because it, by default, sends a blank "HELO" rather than
        a "HELO hostname" when using the 'system' or 'telnet' mail method.

        The fix is to include -DZMAILER in the compilation, which will
        cause it to use "HELO hostname" (which Z-mail apparently requires
        as well. :)

PH
        PH support is provided by Mark Roth <roth@uiuc.edu>.  The map is
        described at http://www-dev.cites.uiuc.edu/sendmail/ .

        NOTE: The "spacedname" pseudo-field which was used by earlier
        versions of the PH map code is no longer supported!  See the URL
        listed above for more information.

        Please contact Mark Roth for support and questions regarding the
        map.

TCP Wrappers
        If you are using -DTCPWRAPPERS to get TCP Wrappers support you will
        also need to install libwrap.a and modify your site.config.m4 file
        or the generated Makefile to include -lwrap in the LIBS line
        (make sure that INCDIRS and LIBDIRS point to where the tcpd.h and
        libwrap.a can be found).

        TCP Wrappers is available at ftp://ftp.porcupine.org/pub/security/.

        If you have alternate MX sites for your site, be sure that all of
        your MX sites reject the same set of hosts.  If not, a bad guy whom
        you reject will connect to your site, fail, and move on to the next
        MX site, which will accept the mail for you and forward it on to you.

Regular Expressions (MAP_REGEX)
        If sendmail linking fails with:

                undefined reference to 'regcomp'

        or sendmail gives an error about a regular expression with:

                pattern-compile-error: : Operation not applicable

        Your libc does not include a running version of POSIX-regex.  Use
        librx or regex.o from the GNU Free Software Foundation,
        ftp://ftp.gnu.org/pub/gnu/rx-?.?.tar.gz or
        ftp://ftp.gnu.org/pub/gnu/regex-?.?.tar.gz.
        You can also use the regex-lib by Henry Spencer,
        ftp://ftp.funet.fi/pub/languages/C/spencer/regex.shar.gz
        Make sure, your compiler reads regex.h from the distribution,
        not from /usr/include, otherwise sendmail will dump a core.

Fedora Core 5, 64 bit version
        If the ld stage fails with undefined functions like
        __res_querydomain, __dn_expand
        then add these lines to devtools/Site/site.config.m4

        APPENDDEF(`confLIBDIRS', `-L/usr/lib64')
        APPENDDEF(`confINCDIRS', `-I/usr/include/bind9')

        and rebuild (sh ./Build -c).

        Problem noted by Daniel Krones, solution suggested by
        Anthony Howe.


+--------------+
| MANUAL PAGES |
+--------------+

The manual pages have been written against the -man macros, and
should format correctly with any reasonable *roff.


+-----------------+
| DEBUGGING HOOKS |
+-----------------+

As of 8.6.5, sendmail daemons will catch a SIGUSR1 signal and log
some debugging output (logged at LOG_DEBUG severity).  The
information dumped is:

 * The value of the $j macro.
 * A warning if $j is not in the set $=w.
 * A list of the open file descriptors.
 * The contents of the connection cache.
 * If ruleset 89 is defined, it is evaluated and the results printed.

This allows you to get information regarding the runtime state of the
daemon on the fly.  This should not be done too frequently, since
the process of rewriting may lose memory which will not be recovered.
Also, ruleset 89 may call non-reentrant routines, so there is a small
non-zero probability that this will cause other problems.  It is
really only for debugging serious problems.

A typical formulation of ruleset 89 would be:

        R$*             $@ $>0 some test address


+-----------------------------+
| DESCRIPTION OF SOURCE FILES |
+-----------------------------+

The following list describes the files in this directory:

Build           Shell script for building sendmail.
Makefile        A convenience for calling ./Build.
Makefile.m4     A template for constructing a makefile based on the
                information in the devtools directory.
README          This file.
TRACEFLAGS      My own personal list of the trace flags -- not guaranteed
                to be particularly up to date.
alias.c         Does name aliasing in all forms.
aliases.5       Man page describing the format of the aliases file.
arpadate.c      A subroutine which creates ARPANET standard dates.
bf.c            Routines to implement memory-buffered file system using
                hooks provided by libsm now (formerly Torek stdio library).
bf.h            Buffered file I/O function declarations and
                data structure and function declarations for bf.c.
collect.c       The routine that actually reads the mail into a temp
                file.  It also does a certain amount of parsing of
                the header, etc.
conf.c          The configuration file.  This contains information
                that is presumed to be quite static and non-
                controversial, or code compiled in for efficiency
                reasons.  Most of the configuration is in sendmail.cf.
conf.h          Configuration that must be known everywhere.
control.c       Routines to implement control socket.
convtime.c      A routine to sanely process times.
daemon.c        Routines to implement daemon mode.
deliver.c       Routines to deliver mail.
domain.c        Routines that interface with DNS (the Domain Name
                System).
envelope.c      Routines to manipulate the envelope structure.
err.c           Routines to print error messages.
headers.c       Routines to process message headers.
helpfile        An example helpfile for the SMTP HELP command and -bt mode.
macro.c         The macro expander.  This is used internally to
                insert information from the configuration file.
mailq.1         Man page for the mailq command.
main.c          The main routine to sendmail.  This file also
                contains some miscellaneous routines.
makesendmail    A convenience for calling ./Build.
map.c           Support for database maps.
mci.c           Routines that handle mail connection information caching.
milter.c        MTA portions of the mail filter API.
mime.c          MIME conversion routines.
newaliases.1    Man page for the newaliases command.
parseaddr.c     The routines which do address parsing.
queue.c         Routines to implement message queueing.
readcf.c        The routine that reads the configuration file and
                translates it to internal form.
recipient.c     Routines that manipulate the recipient list.
sasl.c          Routines to interact with Cyrys-SASL.
savemail.c      Routines which save the letter on processing errors.
sendmail.8      Man page for the sendmail command.
sendmail.h      Main header file for sendmail.
sfsasl.c        I/O interface between SASL/TLS and the MTA.
sfsasl.h        Header file for sfsasl.c.
shmticklib.c    Routines for shared memory counters.
sm_resolve.c    Routines for DNS lookups (for DNS map type).
sm_resolve.h    Header file for sm_resolve.c.
srvrsmtp.c      Routines to implement server SMTP.
stab.c          Routines to manage the symbol table.
stats.c         Routines to collect and post the statistics.
statusd_shm.h   Data structure and function declarations for shmticklib.c.
sysexits.c      List of error messages associated with error codes
                in sysexits.h.
sysexits.h      List of error codes for systems that lack their own.
timers.c        Routines to provide microtimers.
timers.h        Data structure and function declarations for timers.h.
tls.c           Routines for TLS.
trace.c         The trace package.  These routines allow setting and
                testing of trace flags with a high granularity.
udb.c           The user database interface module.
usersmtp.c      Routines to implement user SMTP.
util.c          Some general purpose routines used by sendmail.
version.c       The version number and information about this
                version of sendmail.

(Version $Revision: 8.393 $, last update $Date: 2013-11-22 20:51:54 $ )