[Chapter 18] 18.8 Alphabetized Reference
Author: Bryan Costales & Eric Allman
Date: 1999-01-06T18:48:41Z

#

| Chapter 18 Compile and Install sendmail |

## 18.8 Alphabetized Reference

In this section we present each `#define` macro (or group of them) in alphabetical order rather than in the order in which they appear in your Makefile.

Note that the Tune column of Table 18.3 recommends whether or not you should adjust (tune) the values for any particular `#define`. Those marked tune may be adjusted from within your Makefile. Those marked with port should be changed only in the rare event that you need to port sendmail to a new operating system. [11] Those marked with debug should only be defined during porting to help debug the new binary but (for security reasons) should never be defined for the final production version.

> [11] But note that final porting should be done in conf.h and conf.c instead of Makefile.

Also note that the -d column shows which debugging switches can be used to determine whether the corresponding macro was defined when a sendmail binary was compiled (see Section 37.5.1, -d0.1 for a description of this process).

Table 18.3: #define Macros for Compiling sendmail
#define |  | Tune | -d | Description
--- | --- | --- | --- | ---
AUTO_NIS_ALIASES | Section 18.8.1 | Tune |  | Add fallback alias techniques
BROKEN_RES_SEARCH | Section 18.8.2, BROKEN-RES-SEARCH | Port |  | Broken resolver fix (e.g. Ultrix)
BSD4_3 | Section 18.8.3, BSD4-3 | Port |  | Use BSD 4.3 style signal handling
BSD4_4 | Section 18.8.4, BSD4-4 | Port |  | Compile for BSD 4.4 UNIX
DSN | Section 18.8.5, DSN | Tune |  | Support Delivery Status Notification
ERRLIST_PREDEFINED | Section 18.8.6 | Port |  | Correct type conflicts on sys_errlist
_FFR_... | Section 18.8.7, -FFR-... | Debug |  | For Future Release
FORK | Section 18.8.8, FORK | Port |  | The type of fork(5) to use
HAS... | Section 18.8.9, HAS... | Port | 0.10 | Has specific system call support
HESIOD | Section 18.8.10 | Tune | 0.1 | Support hesiod database maps
HES_GETMAILHOST | Section 18.8.11, HES-GETMAILHOST | Tune | 0.1 | Use hesiod hes_getmailhost(3)
IDENTPROTO | Section 18.8.12, IDENTPROTO | Port | 0.10 | See Timeout.ident (Section 34.8.70.10)
IP_SRCROUTE | Section 18.8.13, IP-SRCROUTE | Port | 0.10 | Add IP source-routing to $_
LA_TYPE | Section 18.8.14, LA-TYPE | Port | 3.5 | Define your load-average support
LDAPMAP | Section 18.8.15 | Tune | 0.1 | Enable use of ldap databases
LOG | Section 18.8.16, LOG | Tune | 0.1 | Perform logging
LOTUS_NOTES_HACK | Section 18.8.17, LOTUS-NOTES-HACK | V8.7.5 |  | Strip newlines from `From:` headers
MATCHGECOS | Section 18.8.18, MATCHGECOS | Tune | 0.1 | Support for fuzzy name matching
MAX... | Section 18.8.19, MAX... | Tune |  | Redefine maximums
MEMCHUNKSIZE | Section 18.8.20, MEMCHUNKSIZE | Tune |  | Specify memory allocation size
MIME7TO8 | Section 18.8.21, MIME7TO8 | Tune | 0.1 | Support MIME 7- to 8-bit conversion
MIME8TO7 | Section 18.8.22, MIME8TO7 | Tune | 0.1 | Support MIME 8- to 7-bit conversion
NAMED_BIND | Section 18.8.23 | Tune | 0.1 | Support DNS name resolution
NDBM | Section 18.8.24 | Tune | 0.1 | Support UNIX ndbm(3) Databases
NEED... | Section 18.8.25, NEED... | Port |  | Something amiss with your OS?
NET... | Section 18.8.26, NET... | Tune | 0.1 | Select network type
NETINFO | Section 18.8.27 | Tune | 0.1 | Support NeXT netinfo(3) databases
NEWDB | Section 18.8.28 | Tune | 0.1 | Support Berkeley db(3) Databases
NIS | Section 18.8.29 | Tune | 0.1 | Support nis maps
NISPLUS | Section 18.8.30 | Tune | 0.1 | Support nis+ maps
NO_GROUP_SET | Section 18.8.31, NO-GROUP-SET | Port |  | Prevent multi-group file access
NOTUNIX | Section 18.8.32, NOTUNIX | Port | 30.2 | Exclude From line support
OLD_NEWDB | Section 18.8.33 | Port | 0.1 | Support the old form of db(3)
_PATH... | Section 18.8.34 | Debug |  | Hard-code paths inside `sendmail`
PICKY... | Section 18.8.35, PICKY... | Tune |  | Make a pickier sendmail
PSBUFSIZE | Section 18.8.36, PSBUFSIZ | Tune |  | Size of prescan() buffer
QUEUE | Section 18.8.37, QUEUE | Tune |  | Enable queueing
QUEUESEGSIZE | Section 18.8.38, QUEUESEGSIZE | Tune |  | Amount to grow queue work list
SCANF | Section 18.8.39, SCANF | Tune | 0.10 | Support scanf(3) with F command
SFS_TYPE | Section 18.8.40, SFS-TYPE | Port |  | How to determine free disk space
SMTP | Section 18.8.41, SMTP | Tune |  | Enable SMTP
SMTPDEBUG | Section 18.8.42, SMTPDEBUG | Debug |  | Enable remote debugging
SMTPLINELIM | Section 18.8.43, SMTPLINELIM | n/a |  | Default for obsolete F=L flag
SOLARIS | Section 18.8.44, SOLARIS | Port |  | Support Sun's Solaris 2.x
SPT_TYPE | Section 18.8.45, SPT-TYPE | Port |  | Adapt/exclude process title support
SUID_ROOT_FILES_OK | Section 18.8.46, SUID-ROOT-FILES-OK | Debug | 0.1 | Allow root delivery to files
SYSLOG_BUFSIZE | Section 18.8.47, SYSLOG-BUFSIZE | Port |  | Limit syslog(3) buffer size
SYSTEM5 | Section 18.8.48, SYSTEM5 | Port | 0.10 | Support SysV derived machines
SYS5SIGNALS | Section 18.8.48 | Port | 0.10 | Use SysV style signals
TCPWRAPPERS | Section 18.8.49, TCPWRAPPERS | Tune | 0.1 | Use libwrap.a for connects
TOBUFSIZE | Section 18.8.50, TOBUFSIZE | Tune |  | Set buffer for recipient list
TRUST_POPEN | Section 18.8.51, TRUST-POPEN | Debug |  | Allow use of popen(3)
TTYNAME | Section 18.8.52, TTYNAME | Debug | 35.9 | Set $y to tty name (obsolete)
UDB_DEFAULT_SPEC | Section 18.8.53 | Tune |  | Default User Database location
USERDB | Section 18.8.54 | Tune | 0.1 | Support the User Database
USESETEUID | Section 18.8.55, USESETEUID | Port | 0.10 | Support seteuid(2) identity changes
WILDCARD_SHELL | Section 18.8.56, WILDCARD-SHELL | Debug |  | Redefine wildcard shell
XDEBUG | Section 18.8.57, XDEBUG | Debug | 0.1 | Support sanity checks

### 18.8.1 AUTO-NIS-ALIASES

Add fallback alias techniques

(tune with DBMDEF= in Makefile)

> Ordinarily, sendmail will first look for a service-switch (see Section 34.8.61) to see how it should look up its aliases. If it finds one, and if the service aliases is listed, it uses the techniques listed with the service-switch to look up its aliases. In the absence of a service-switch, or if the service-switch could not be opened, sendmail's fallback position is to use the technique called files to look up its aliases.

> This AUTO_NIS_ALIASES definition, when specified during compilation, also causes sendmail to automatically add the technique nis if NIS was defined or nis+ if NISPLUS was defined:

> >     DBMDEF= -DNIS -DAUTO_NIS_ALIASES
> >     DBMDEF= -DNISPLUS -DAUTO_NIS_ALIASES

> The first line causes the fallback list of techniques to become files then nis, and the second causes it to become files then nisplus. Note that AUTO_NIS_ALIASES is not defined in any Makefile distributed with sendmail.

### 18.8.2 BROKEN-RES-SEARCH

Broken resolver fix (e.g. Ultrix)

(port, edit conf.h)

> On Ultrix, and possibly other systems, the res_search(2) routine incorrectly sets h_errno to 0 instead of HOST_NOT_FOUND if a host name is unknown. On such systems you can define BROKEN_RES_SEARCH in your Makefile, which tells sendmail to consider 0 the same as HOST_NOT_FOUND:

> >     ENVDEF= -DBROKEN_RES_SEARCH

> As distributed, this is not declared for any of the supplied Makefile files. If you are running Ultrix you should test your resolver library. If it fails, you should upgrade to the latest resolver library. If, for some reason, upgrading is not possible, you may define this as a workaround. When porting to a new system, you can test with the above ENVDEF= statement and, if successful, put a permanent porting entry into conf.h.

### 18.8.3 BSD4-3

Use old style signal handling

(port, edit conf.h)

> Old BSD-based versions of UNIX, such as SunOS 4.0.x and BSD 4.3, used the signal(2) and sigsetmask(2) calls to set and release signals. Modern versions of UNIX use the sigaction(2) and sigprocmask(2) pair of routines. For all currently supported systems, BSD4_3 is already correctly defined in src/Makefiles or in conf.h. You should need to define BSD4_3 only if you are porting to a previously unsupported old BSD-based system:

> >     ENVDEF= -DBSD4_3

> When porting to a new system, you can test with the above ENVDEF= statement and, if successful, put a permanent porting entry into conf.h.

### 18.8.4 BSD4-4

Compile for BSD 4.4 Unix

(port, edit conf.h)

> BSD4_4 will automatically be defined when sendmail is built under the BSD 4.4 release of UNIX. You will need to redefine this only if you are porting to a new operating system that is based on BSD 4.4.

### 18.8.5 DSN

Support Delivery Status Notification

(tune with ENVDEF= in Makefile)

> Delivery Status Notification (DSN) replaces certain SMTP error codes and the `Return-Receipt-To:` header (Section 35.10.29, Return-Receipt-To:) as a means of handling multiple delivery status requests and problems. DSN is an improvement over earlier mechanisms for returning delivery status information. It can, for example, supply different status information for each recipient when multiple recipients are specified. It can also be used to generate return receipts on a per recipient basis. DSN status is returned in the MIME encapsulated portion of a mail message's body.

> DSN is defined in RFC1891, RFC1892, RFC1893, and RFC1894. If you wish to exclude DSN support (not recommended), you may turn it off like this:

> >     ENVDEF=  -DDSN=0

> >           turn off DSN support

> MIME is described under the `EightBitMode` (`8`) option (see Section 34.8.22, EightBitMode (8)).

### 18.8.6 ERRLIST-PREDEFINED

Correct conflicts on sys-errlist

(port, edit conf.h)

> Some systems define a type for sys_errlist[] that differs from the internal declaration made by sendmail. In such instances you will get a warning about sys_errlist being redefined when you compile. Such warnings are usually harmless, but they are unattractive. To eliminate them, add the following to your Makefile:

> >     ENVDEF= -DERRLIST_PREDEFINED

> When porting to a new system, you can test with the above ENVDEF= statement and, if successful, put a permanent porting entry into conf.h.

### 18.8.7 -FFR-...

For Future Release

(debug with ENVDEF= in Makefile)

> Most releases of sendmail contain, within the C language code, sections that are commented out. These are initial stabs at solutions that either did not work as is, are incomplete or untested, or are dreams for the future.

> If you have a good reason and thoroughly understand the code and why it is excluded (and if you are brave), you may include it by adding an appropriate _FFR_ (For Future Release) definition to ENVDEF= in Makefile:

> >     ENVDEF= -D_FFR_what

> Here, `what` describes the appropriate future item that you want to include (as found in the source). We categorize this as a debugging technique (not a porting or tuning one) because you may want to include future code for testing, but should probably not include it in your production version.

### 18.8.8 FORK

The type of fork to use

(port, edit conf.h)

> The sendmail program forks often to do its job in the most efficient way possible. Prior to V8.8, sendmail used vfork(2) whenever possible. Beginning with V8.8, sendmail now defaults to fork(2). [12] You should have to redefine FORK only when porting to a new system or when you are certain that vfork(2) is indeed faster on your system and is reliable.

> > [12] Bugs in the interaction between NIS and vfork(2) at the system level with Solaris and systems that lacked vfork(2) altogether, such as IRIX, caused V8.8 to favor fork(2). This is really okay because in modern systems, fork(2) is just as fast as vfork(2).

> >     ENVDEF= -DFORK=vfork

> You can test with the above ENVDEF= statement and, if successful, put a permanent porting entry into conf.h.

### 18.8.9 HAS...

Has specific system call support

(port, edit conf.h)

> Macros that begin with HAS tell sendmail whether or not your system supports (has) certain system-library routines. In general, you should need to define or undefine the macros shown in Table 18.4 only if you are porting sendmail to a new system. In that instance you should also read src/READ_ME for the latest information and pitfalls.

> Each of these is turned on or off with an assignment of 1 or 0:

> >     ENVDEF=  -DHASSETSID=1       turn on
> >     ENVDEF=  -DHASSETSID=0       turn off

> Turning on tells sendmail that your site has support for this system call (setsid(2) in this instance). Turning off tells sendmail to work around the lack of that support. When porting to a new system, you can test with one of the above ENVDEF= statements and, if successful, put a permanent porting entry into conf.h.

> These have probably been correctly defined for your system already. Therefore you should need to change them only when porting sendmail to a completely new system.

> Table 18.4: HAS... #defines for Specific System Call Support
> #define | System Call
> --- | ---
> HASFCHMOD | fchmod(2)
> HASFLOCK | flock(2)
> HASGETDTABLESIZE | getdtablesize(2)
> HASGETUSERSHELL | getusershell(3)
> HASINITGROUPS | initgroups(3)
> HASLSTAT | lstat(2)
> HASSETREUID | setreuid(2)
> HASSETRLIMIT | setrlimit(2)
> HASSETSID | setsid(2)
> HASSETUSERCONTEXT | setusercontext(3)
> HASSETVBUF | setvbuf(3)
> HASSIGSETMASK | sigsetmask(2)
> HASSNPRINTF | snprintf(3) and vsnprintf(3)
> HASULIMIT | ulimit(2)
> HASUNAME | uname(2)
> HASUNSETENV | unsetenv(3)
> HASWAITPID | waitpid(2)

> If you are running a precompiled binary of sendmail, you can determine whether any of these were defined when sendmail was compiled by using the `-d0.10` debugging switch (see Section 37.5.3, -d0.10).

### 18.8.10 HESIOD

Support hesiod database maps

(tune with DBMDEF= in Makefile)

> Named after the 8th century B.C.E. [13] Greek poet Hesiod, the hesiod system is a network information system developed as Project Athena. Information that is shared among many machines on a network can be accessed by each machine using a common set of library routines. Files that are commonly represented in this form are the passwd(4) and aliases(4) files used by sendmail. The hesiod system is patterned after the Internet Domain Naming System and uses modified BIND source:

> > [13] Before Christian Era, although an alternative proposal that is making the rounds calls for signed years, thus the -8th century.

> >     DBMDEF= -DHESIOD

> If HESIOD is defined when sendmail is built, support is included to look up aliases and user information via the hesiod interface. Support is also included to declare and use hesiod class maps (see Section 33.3.2, "The class") with the `K` configuration command. Support is also included for the User Database if USERDB is also defined.

> Hesiod documentation and source are available from:

> > ftp://athena-dist.mit.edu/pub/ATHENA

> If you are running a precompiled sendmail binary, you may use the `-d0.1` switch (see Section 37.5.1) to determine whether HESIOD support is included.

### 18.8.11 HES-GETMAILHOST

Use hesiod hes-getmailhost()

(tune with ENVDEF= in Makefile)

> The MIT distribution of hesiod supports the hes_getmailhost(3) call for looking up a user's postoffice. If your site is running MIT's hesiod, you should define this. If your are running DEC's hesiod, you should not.

> >     ENVDEF= -DHES_GETMAILHOST

> HES_GETMAILHOST is by default not defined. If you need it, you must define it in your Makefile. If you are running a precompiled version of sendmail, you may use the `-d0.1` debugging switch (see Section 37.5.1) to determine whether HES_GETMAILHOST has been included. The `-d28.8` (see Section 37.5.100, -d28.8) debugging flag can be used to trace the behavior of the hes_getmailhost(3) routine.

### 18.8.12 IDENTPROTO

See Timeout.ident in Section 34.8.70.10

(port)

> Defining out IDENTPROTO neither includes nor excludes RFC1413 code. All it does is change the default value for the `Timeout.ident` option (see Section 34.8.70.10):

> >     ENVDEF= -DIDENTPROTO=0           set Timeout.ident=0 by default
> >     ENVDEF= -DIDENTPROTO=1           set Timeout.ident=30 by default

> If you are running a precompiled sendmail binary, you may use the `-d0.10` switch (see Section 37.5.3) to determine whether IDENTPROTO was defined as nonzero.

### 18.8.13 IP-SRCROUTE

Add IP source-routing to $-

(port, edit conf.h)

> Mail is normally transported over networks with TCP/IP. At the IP layer, packets are usually constructed to be point-to-point - from one host to another. IP packets can also be constructed to contain source-routing information - from one host, through a second, then to a final host.

> Although such source routing (when used) is generally legitimate, it can also be used to generate fraudulent mail. V8.7 sendmail attempts to extract source-routing information from the initial connection's IP information. If any is found, sendmail adds that information to the `$_` macro (see Section 31.10.1, $-) for use in the `Received:` header (see Section 35.10.25, Received:). The `$_` macro is usually used like this:

> >     Received: from $s ($_) ...

> where `$_` will contain information like that shown below when IP source-routing information is found:

> >            IP source-routing information

> >     user@host.domain [!@hostC@hostB:hostA]

> >     RFC1413 identd information

> IP source-routing information is presented inside square brackets. If routing is strict, the information is prefixed with an exclamation mark. The format of the information is made to resemble that of source-route addressing (see the `DontPruneRoutes` option, Section 34.8.20, DontPruneRoutes (R)). In this example the IP packets will go first to `hostC`, then to `hostB`, and finally to `hostA`.

> The inclusion of code to support this reporting is determined by the IP_SRCROUTE definition in your Makefile. It is predefined correctly for all supported systems in conf.h, so you should need to redefine it only if you are porting sendmail to a completely new system. Be sure to read src/READ_ME for the latest information about IP_SRCROUTE.

> If you are running a precompiled sendmail binary, you may use the `-d0.10` switch (see Section 37.5.3) to determine whether IP_SRCROUTE support was included.

### 18.8.14 LA-TYPE

Define your load-average support

(port, edit conf.h)

> The load average is the average number of blocked processes (processes that are runnable but not able to run because of a lack of resources) over the last minute. The sendmail program can vary its behavior appropriately as the load average changes. Thresholds for change are defined by the options shown in Table 34.9 (see Section 34.6.4, "Controlling Machine Load").

> The method that is used to get the current load average from the operating system varies widely. This LA_TYPE definition determines which method to use. It is correctly defined inside conf.h for all currently supported operating systems. Porting sendmail to a new system may require that you define LA_TYPE yourself. The possible values and their meanings are shown in Table 18.5.

> Table 18.5: LA_ Methods for Getting the Load Average
> LA_ | Does What
> --- | ---
> LA_ZERO | Always returns 0. Essentially disables load average checking. This is portable to all systems.
> LA_INT | Read /dev/kmem for the symbol avenrun. If found, interpret the result as a native (usually long) integer.
> LA_FLOAT | Read /dev/kmem for the symbol avenrun. If found, interpret the result as a floating-point value.
> LA_SHORT | Read /dev/kmem for the symbol avenrun. If found, interpret the result as a short integer.
> LA_SUBR | Call the library routine getloadavg(3) and use the result returned.
> LA_MACH | Call the MACH-specific processor_set_info(2) routine and use the result returned.
> LA_PROCSTR | Read the Linux-specific /proc/loadavg file and interpret the result as a floating-point value.
> LA_READKSYM | Use the (some SysV versions) ioctl of MIOC_READKSYM to read /dev/kmem.
> LA_DGUX | DG/UX specific support for using the pstat_getdynamic(2)function to read the load average.

> The LA_INT, LA_SHORT, LA_FLOAT, and LA_READKSYM settings require additional tuning. For these, three additional definitions are used as shown in Table 18.6.

> Table 18.6: Tuning for LA_INT, LA_SHORT, LA_FLOAT, and LA_READKSYM
> #define | Tunes
> --- | ---
> FSHIFT | Number of bits to shift right when using LA_INT, LA_SHORT, and LA_READKSYM. Default is 8.
> _PATH_UNIX | The pathname of your kernel. This is required for LA_INT and LA_SHORT. Default is /unix for SysV; /hp_ux for HP/UX V9; /stand/unix for HP/UX V10, News, and UXP/OS; /dev/ksyms for Solaris; /dynix for DYNIX; otherwise /vmunix.
> _PATH_KMEM | The pathname of your kernel memory. This is required for LA_INT, LA_SHORT, LA_FLOAT, and LA_READKSYM. Default is /dev/kmem.
> LA_AVENRUN | The name of the kernel variable that holds the load average. Used by LA_INT, LA_SHORT, and LA_FLOAT. Default is averun for SysV, otherwise _averun.
> NAMELISTMASK | The mask to bitwise-AND against the return value of nlist(3). If this is undefined, the return value is used as is. A common value is 0x7fffffff to strip off the high bit.

### 18.8.15 LDAPMAP

Enable use of ldap databases

(tune with DBMDEF= in Makefile)

> LDAP stands for Lightweight Directory Access Protocol. LDAP provides lightweight access to the X.500 directory and is defined in RFC1777 and RFC1778.

> The software and documentation for LDAP is available from

> > ftp://terminator.rs.itd.umich.edu/ldap/

> It is used by defining a map class called `ldapx` (see Section 33.8.9, ldapx) in your configuration file. Its use is enabled by defining LDAPMAP at compile time:

> >     DBMDEF=LDAPMAP

### 18.8.16 LOG

Perform logging

(port, edit conf.h)

> If defined, LOG enables sendmail to use the syslog(3) facility to log error messages and other useful information that is often important for security and debugging. Logging and syslog(3) are described in Chapter 26, Logging and Statistics. Defining LOG should be considered mandatory, and it should be turned off only if you have a well-thought-out reason for doing so. LOG cannot be turned off in the Makefile. Instead, you must edit conf.h directly and undefine it by commenting it out:

> >     /* # define LOG                 /* enable logging - don't turn off */

> >     comment out to remove support

> LOG requires that your system support syslog(3). If you lack syslog(3), consider porting it to your system.

> Defining LOG is meaningless unless the `LogLevel` (`L`) option (see Section 34.8.33, LogLevel (L)) is also nonzero. Fortunately, this is usually the case because the default is 9.

> See also SYSLOG_BUFSIZE for a way to tune syslog(3)'s buffer size if necessary.

> If you are running a precompiled sendmail binary, you may use the `-d0.1` switch to determine whether LOG support was included (see Section 37.5.1).

### 18.8.17 LOTUS-NOTES-HACK

Strip newlines from From: header

(V8.7.2 through V8.7.5 only)

> The Lotus Notes mail-gateway SMTP software can produce sender header lines that contain newlines when the username part becomes too long:

> >     From: Long Full Name/LongSite/Country
> >       <user@site.domain>

> Although perfectly legal under RFC822, such split sender headers can cause MUAs to fail in ways that are difficult to diagnose. If your site receives mail from Lotus Notes gateways, you should define LOTUS_NOTES_HACK when compiling sendmail:

> >     ENVDEF= -DLOTUS_NOTES_HACK

> Defining LOTUS_NOTES_HACK causes sendmail to include code in support of the `SingleLineFromHeader` option (see Section 34.8.63, SingleLineFromHeader). Setting that option to true causes the newlines in the above address to be stripped and produces a single line:

> >     From: Long Full Name/LongSite/Country <user@site.domain>

> If you are running a precompiled sendmail binary, you can define `SingleLineFromHeader` in your configuration file. If you don't get a warning about a bad option name, then you have this support. Note that under V8.8 sendmail, LOTUS_NOTES_HACK is no longer required for `SingleLineFromHeader` support.

### 18.8.18 MATCHGECOS

Support fuzzy name matching

(tune with ENVDEF= in Makefile)

> Defining MATCHGECOS causes code to be included inside sendmail for support of limited fuzzy name matching. This process is described under the `MatchGECOS` (`G`) option (see Section 34.8.34, MatchGECOS (G)). MATCHGECOS is normally defined by default. If you want to turn it off, use ENVDEF= in Makefile:

> >     ENVDEF= -DMATCHGECOS=0

> If you are running a vendor-supplied binary, you can check to see whether MATCHGECOS was defined by using the `-d0.1` debugging switch (see Section 37.5.1).

### 18.8.19 MAX...

Redefine maximums

(port, edit specific files)

> In porting sendmail to a new system or tuning sendmail for special needs, it may be necessary to adjust one of its defined maximums. These cannot be tuned in Makefile. Instead, each needs to be changed in the file indicated by the third column of Table 18.7. In general, maximums should never be lowered without first examining the code for possible side effects; also, review the code to see whether any minimums are required or whether there are warnings about maximums.

> Table 18.7: MAX... #defines to Redefine Maximums
> #define | Default | File | Maximum
> --- | --- | --- | ---
> MAXALIASDB | 12 | conf.h | Number of alias databases
> MAXATOM | 200 | conf.h | Atoms (tokens) in an address
> MAXDNSRCH | 6 | domain.c | Possible domains to search
> MAXHOSTNAMELEN | 256 | conf.h | Length of a hostname
> MAXKEY | 128 | conf.h | Length of a database key
> MAXLINE | 2048 | conf.h | Length of an input line
> MAXMAILERS | 25 | conf.h | Number of delivery agents
> MAXMAPSTACK | 12 | conf.h | Size of sequenced map stack
> MAXMIMEARGS | 20 | conf.h | Arguments per `Content-Type:` header
> MAXMXHOSTS | 100 | conf.h | Number of per host MX records
> MAXMIMENESTING | 20 | conf.h | Multipart MIME nesting depth
> MAXNAME | 256 | conf.h | Length of a name
> MAXPRIORITIES | 25 | conf.h | Number of Priority lines
> MAXPV | 40 | conf.h | Arguments to a delivery agent
> MAXRULERECURSION | 50 | conf.c | Ruleset recursion
> MAXRWSETS | 200 | conf.h | Number of rule sets
> MAXTOCLASS | 8 | conf.h | Message timeout classes
> MAXUSERENVIRON | 100 | conf.h | Environment items per delivery agent

> Also see QUEUESEGSIZE and SYSLOG_BUFSIZE for the discussion of two other definitions that affect sizes.

> Note that there are no debugging switches to display compiled maximums. If you are running a binary distribution and a maximum is of concern, you should get the source and build sendmail yourself.

### 18.8.20 MEMCHUNKSIZE

Specify memory allocation size

(tune, edit conf.h)

> When sendmail reads lines of text from the configuration file or from `qf` queue files, it calls an internal routine named fgetfolded(). That routine is initially passed a buffer of size MAXLINE into which to fit the read line. If the line is longer than MAXLINE, the sendmail program dynamically increases the space required to hold the line by MEMCHUNKSIZE.

> When collecting the headers of a mail message, sendmail also begins with a buffer sized to MAXLINE. If a header arrives that is larger than MAXLINE characters, sendmail will increase the size of its buffer by MEMCHUNKSIZE as many times as is necessary to fully contain that header's data.

> The default value assigned to MEMCHUNKSIZE is 1024 bytes. If you need to change that value (for example, to port to a new system's strange malloc(3) requirements or for performance reasons), you must edit conf.h:

> >     # define MEMCHUNKSIZE   1024            /* chunk size for memory allocation */

> >                          change this

### 18.8.21 MIME7TO8

Support MIME 7- to 8-bit conversion

(tune with ENVDEF= in Makefile)

> V8.8 sendmail contains the internal ability to convert messages that were converted into either quoted-printable or base64 (see Section 34.8.22) back into their original eight-bit form. The decision of whether or not to do this conversion is based on the `F=9` delivery agent flag (see Section 30.8.6, F=9).

> Defining MIME7TO8 to a value of 1 causes support for conversion to be included in sendmail. It is defined as 1 by default. To disable the inclusion of conversion code, use ENVDEF= in Makefile to define it as 0:

> >     ENVDEF= -DMIME7TO8=0

> >             exclude support

> Unless you have a compelling reason to do otherwise, we recommend that MIME7TO8 remain enabled.

> If you are running a precompiled sendmail binary, you may use the `-d0.1` switch to determine whether MIME7TO8 support (see Section 37.5.1) was included.

### 18.8.22 MIME8TO7

Support MIME 8- to 7-bit conversion

(tune with ENVDEF= in Makefile)

> V8 sendmail contains the internal ability to convert 8-bit MIME message contents into 7-bit MIME so that mail can be transported to non-8-bit gateways. The methods used and the circumstances required to trigger conversion are described under the `EightBitMode` (`8`) option (see Section 34.8.22). The conversion itself can be watched with the `-d43` debugging switch (see Section 37.5.150, -d43.1).

> Defining MIME8TO7 to a value of 1 causes support for conversion to be included in sendmail. It is defined as 1 by default. To disable the inclusion of conversion code, use ENVDEF= in Makefile to define it as 0:

> >     ENVDEF= -DMIME8TO7=0

> >             exclude support

> One side effect of excluding MIME8TO7 support is that defining it to 0 causes all MIME support to also be excluded. Unless you have a compelling reason to do otherwise, we recommend that MIME8TO7 remain enabled.

> If you are running a precompiled sendmail binary, you may use the `-d0.1` switch to determine whether MIME8TO7 support (see Section 37.5.1) was included.

### 18.8.23 NAMED-BIND

Support DNS name resolution

(tune with ENVDEF= in Makefile)

> The sendmail program automatically takes advantage of DNS lookups or MX records to resolve addresses and canonical hostnames. If your site is a UUCP-only site (or is otherwise not connected to the Internet) and does not run named(8) locally, you should probably disable NAMED_BIND:

> >     ENVDEF= -DNAMED_BIND=0

> >                  disable DNS lookups

> If you are not currently running named(8) but plan to connect to the Internet, you should define NAMED_BIND but set the `ResolverOptions` (`I`) (see Section 34.8.55, ResolverOptions (I)) to false in the configuration file. Later, when you connect to the Internet, you can then simply change it to true. (See also the service-switch file, Section 34.8.61, for an another way to achieve the same effect.)

> If you are running a precompiled sendmail binary, you may use the `-d0.1` switch to determine whether NAMED_BIND support was included (see Section 37.5.1).

### 18.8.24 NDBM

Support Unix ndbm(3) Databases

(tune with DBMDEF= in Makefile)

> The ndbm(3) form of database uses two files (.pag and .dir) for each database. Databases cannot be shared by different architectures across a network. If you intend to support aliasing in an efficient manner, you should at least define this NDBM (or NEWDB described below) in your Makefile.

> >     DBMDEF= -DNDBM

> The ndbm(3) routines are used primarily to look up aliases. They can also be used to declare dbm class maps (see Section 33.3.2) with the `K` configuration command.

> Library routines to support ndbm(3) are available with most modern versions of UNIX. You may have to specify library support with a `-lndbm` in the LIBS= line of your Makefile. If you are running a precompiled sendmail binary, you may use the `-d0.1` switch to determine whether ndbm(3) support was included (see Section 37.5.1).

### 18.8.25 NEED...

Something amiss with your OS?

(port, edit conf.h)

> The sendmail program requires certain C language library routines to exist. If any is missing from your library, define one of the needs listed in Table 18.8 and sendmail will try to emulate it.

> Each is defined with ENVDEF= in Makefile by setting it to a value of 1 (NEEDPUTENV is an exception in that 1 or 2 can be used).

> >     ENVDEF= -DNEEDFSYNC=1

> When porting to a new system, you can test with this ENVDEF= statement and, if successful, put a permanent porting entry into conf.h. Note that these are correctly defined for all currently supported systems. You should need to redefine them only if you are porting sendmail to a completely new system.

> Table 18.8: Define Replacements for Missing C Library Routines
> #define | Emulates
> --- | ---
> NEEDFSYNC | Replaces a missing fsync(2). The sendmail program will try to simulate it by using fcntl(2), if available; otherwise, sendmail will not "sync" to disk. This latter circumstance is undesirable and may result in unreliable mail delivery, but it works.
> NEEDGETOPT | The sendmail program calls getopt(3) twice when parsing its command-line arguments. Some version of getopt(3) do odd things when called twice. If yours is one of these, replace it.
> NEEDPUTENV | Replace a missing putenv(3). If this is defined as 1, sendmail emulates by using setenv(3). If this is defined as 2, sendmail emulates by directly modifying the environmental section of memory.
> NEEDSTRSTR | Replace a missing strstr(3) with a well-written internalversion.
> NEEDSTRTOL | Replace a missing strtol(3) with a well-written internalversion.
> NEEDVPRINTF | Replace a missing vprintf(3). Note that the emulation supplied is not very elegant. It may not even work on some systems. See conf.h for a glimpse of systems that require this.

> If you are running a precompiled sendmail binary, there is no way to discover whether any of these were defined when it was built.

### 18.8.26 NET...

Define Network Support

(tune with ENVDEF= in Makefile)

> V8 sendmail is designed to support four kinds of networks, as listed in Table 18.9. Currently, only NETINET and NETISO are supported.

> Table 18.9: Define for Network Support
> Define | Description
> --- | ---
> NETINET | A TCP/IP-based network
> NETISO | An ISO 8022 network
> NETNS | A Xerox NS protocol network (tentative)
> NETX25 | A CCITT\*[=a] X.25 network (tentative)

> International Telephone and Telegraph Consultative Committee.

> Stubs are included in the source code for any programmer who is interested in implementing NETNS or NETX25. NETINET is defined by default. If you don't want it, you need to turn it off in your Makefile:

> >     ENVDEF= -DNETINET=0

> NETISO is undefined by default. If you want to include ISO support, you need to specifically define it in your Makefile:

> >     ENVDEF= -DNETISO=1

> Defining NETINET or NETISO has the side effect of causing SMTP and QUEUE also to be automatically defined.

> Defining network support only causes the code for that network to be included in sendmail. The network serviced by a particular invocation of sendmail is selected with the `Family` parameter of the `DaemonPortOptions` (`O`) option (see Section 34.8.13, DaemonPortOptions (O)). In the absence of an option declaration, inet (for NETINET) is used as the default.

> If you are running a precompiled version of sendmail, you can determine which network types are supported by using the `-d0.1` debugging switch (see Section 37.5.1).

### 18.8.27 NETINFO

Support NeXT netinfo(3) databases

(tune with DBMDEF= in Makefile)

> The netinfo(3) form of database is supplied with the NeXT and NeXTSTeP operating systems. It is a network information service that provides file contents such as aliases and passwd, and locations such as the location of the sendmail.cf file. If you are running on a NeXT or under NeXTSTeP, this NETINFO will automatically be defined in your Makefile:

> >     DBMDEF= -DNETINFO

> The netinfo(3) databases can also be used to declare netinfo class maps (see Section 33.3.2) with the `K` configuration command. If you are running a precompiled sendmail binary, you may use the `-d0.1` switch to determine whether NETINFO support was included (see Section 37.5.1).

### 18.8.28 NEWDB

Support Berkeley db(3) Databases

(tune with DBMDEF= in Makefile)

> The db(3) form of database uses a single file and can be shared by different architectures. If you intend to support aliasing in an efficient manner, you should at least define this NEWDB (or the NDBM described above) in your Makefile. The db(3) routines are used to look up aliases and are the routines used by the User Database (see Section 33.5, "The User Database"). They can also be used to declare hash and btree class maps (see Section 33.3.2) with the `K` configuration command.

> The db(3) libraries have overcome many of the limitations of the earlier ndbm(3) libraries. If possible, you should get and install the db(3) libraries before you build sendmail. The db(3) source is available from

> > ftp://ftp.cs.berkeley.edu/ucb/4bsd/db.tar.Z

> Do not use the Net2 distribution. (See OLD_NEWDB below if you already have that distribution and can't easily get rid of it.) The src/READ_ME file contains critical information [14] about installing db(3).

> > [14] Such as why you must remove ndbm.h and ndbm.o from libdb.a before installing it for use by sendmail.

> If you are running a precompiled sendmail binary, you may use the `-d0.1` switch (see Section 37.5.1) to determine whether db(3) support was included in it.

### 18.8.29 NIS

Support for NIS

(tune with DBMDEF= in Makefile)

> If you intend to have sendmail support nis (formerly Yellow Pages) maps, you need to define NIS as part of your DBMDEF= line in Makefile:

> >     DBMDEF= -DNIS

> If NIS is defined, the `AliasFile` (`A`) option can be specified as

> >     OAnis:mail.aliases                 V8.6
> >     O AliasFile=nis:mail.aliases       V8.7 and above (if no service-switch file)

> See Section 34.8.1, AliasFile (A) for more details about the `AliasFile` (`A`) option. See Section 34.8.61 for a description of the `ServiceSwitchFile` option and its effect on nis aliases. Be aware that the above `AliasFile` (`A`) option declaration will override the lack of an nis entry in the service-switch file.

> NDBM also needs to be defined to allow sendmail to rebuild its alias files for use by nis:

> >     DBMDEF= -DNIS -DNDBM

> For this to work, the path of the alias file needs to contain the substring "/yp/". A typical /var/yp/Makefile will contain a line like this:

> >     /usr/lib/sendmail -bi -oA$(YPDBDIR)/$(DOM)/mail.aliases

> Here, $(YPDBDIR)/ is usually /var/yp/, so the substring is found. When "/yp/" is found, sendmail augments the aliases database with two special entries that are needed by nis:

> >     YP_LAST_MODIFIED
> >     YP_MASTER_NAME

> These allow the newly built aliases file to successfully be distributed for use by nis clients. Without these entries you will see an error like that shown below when pushing your nis maps:

> >     Status received from ypxfr on nisslave:
> >             Failed - no local order number in map - use -f flag to ypxfr.

> The solution here is to rebuild sendmail with both NDBM and NIS defined.

> Defining NIS also causes support to be included for declaring and using nis class maps (see Section 33.3.2) with the `K` configuration command.

> Note that defining NIS without also defining NAMED_BIND will cause delivery to MX records to mysteriously fail.

> If you are running a precompiled sendmail binary, you may use the `-d0.1` switch to determine whether NIS support was included (see Section 37.5.1).

### 18.8.30 NISPLUS

Support for NIS+

(tune with DBMDEF= in Makefile)

> If you intend to have sendmail support nisplus maps, you need to define NISPLUS as part of your DBMDEF= line in Makefile. (The use of nisplus aliases and other maps is determined by the /etc/nsswitch.conf file.)

> >     DBMDEF= -DNISPLUS

> If NISPLUS is defined, the `AliasFile` (`A`) option can be used to override the setting of the /etc/nsswitch.conf file:

> >     O AliasFile=nisplus:mail.aliases       V8.7 and above

> Here, `nisplus` aliases will be used even if the /etc/nsswitch.conf file excludes them.

> See Section 34.8.1 for details about the `AliasFile` (`A`) option. Note that NISPLUS is new to V8.7 and not supported under earlier versions of sendmail.

> With NISPLUS defined, support is also included to declare and use nisplus class maps (see Section 33.3.2) with the `K` configuration command.

> If you are running a precompiled sendmail binary, you may use the `-d0.1` switch to determine whether NISPLUS support was included (see Section 37.5.1).

### 18.8.31 NO-GROUP-SET

Prevent multi-group file access

(port, edit conf.h)

> When checking files and directories for group read and write permissions, sendmail checks the group of the controlling user. On systems that allow a user to belong to one group at a time, failure stops here; on systems that allow users to belong to many groups at once, failure causes sendmail to check any other groups to which the controlling user may belong. It finds the list of groups by calling getgrgid(3).

> If your system lacks the getgrgid(3) call or doesn't need it, you should exclude this code by defining NO_GROUP_SET in conf.h. NO_GROUP_SET causes the code containing the call to getgrgid(3) to be excluded from sendmail. Be aware that excluding getgrgid(3) support on systems that need it can cause delivery to files to fail in mysterious ways.

> If you are running a precompiled version of sendmail, be aware that there is no debugging switch that can tell you what the setting of NO_GROUP_SET was set to at compile time.

> Note that NO_GROUP_SET affects only inclusion of the getgrgid(3) system call. See the `DontInitGroups` option (see Section 34.8.19, DontInitGroups) for a means to exclude the getgrgid(3) and initgroups(3) system calls.

### 18.8.32 NOTUNIX

Exclude From line support

(port, edit conf.h)

> Under UNIX a file of many mail messages normally has one message separated from another by a blank line and then a line that begins with the five characters "`From` " (four letters and a space). On such systems, sendmail saves important information from such lines for later use.

> On non-UNIX machines (VMS or MS-DOS) the conventions are different, so you won't want sendmail to treat such lines as special. Similarly, if your UNIX site has converted entirely away from this convention (with mhs or the like), you might not want this special treatment.

> To disable special treatment of "`From` " lines, define the NOTUNIX macro in your Makefile:

> >     ENVDEF= -DNOTUNIX

> When porting to a new system, you can test with this ENVDEF= statement and, if successful, put a permanent porting entry into conf.h. Defining NOTUNIX causes the code for eatfrom() to be excluded from sendmail. The `-d30.2` debugging switch (see Section 37.5.109, -d30.2) can be used to watch eatfrom() and to determine whether NOTUNIX was declared when compiling sendmail.

### 18.8.33 OLD-NEWDB

Support the old form of db(3)

(port with DBMDEF= in Makefile)

> BSDI(BSD/386) 1.0, NetBSD 0.9, and FreeBSD 1.0 were distributed with an old version of the db(3) library. These systems will not use the file locking of the latest version. For such systems you must define

> >     DBMDEF= -DNEWDB -DOLD_NEWDB=1

> >                     don't support new file locking

> Although you can get and install the latest version of db(3), you should not do so unless you can rebuild your entire UNIX system. The old form of database is used throughout, and just building sendmail with the new form will cause password lookups and the like to fail.

> In general, you should never have to declare OLD_NEWDB (instead, we recommend upgrading your operating system). OLD_NEWDB is automatically included in the Makefile for the systems that need it.

### 18.8.34 PATH...

Hardcode paths inside sendmail

(debug with ENVDEF= in Makefile)

> Only a few pathnames are hard-coded into sendmail. The most obvious is its configuration file, because that file lists the locations of nearly all other files. For various reasons a few other file locations are also hard-coded. Here, we describe those that you can change. Note that the general form for all such changes uses the ENVDEF= declaration of your Makefile:

> >     ENVDEF= -D_PATH...=\"/new/path/filename\"

> The new path must be surrounded by backslashed quotation marks so that the compiler will correctly interpret it as a string. /etc/sendmail.cf The sendmail.cf file is pivotal to all of the sendmail program's operations (see Chapter 27, The Configuration File). V8.7 sendmail recommends that it always be called sendmail.cf and always be located in the /etc directory. For testing, debugging, or other legitimate reasons you may prefer to locate that file elsewhere (at least temporarily). You do that with the _PATH_SENDMAILCF definition:

> >     ENVDEF= -D_PATH_SENDMAILCF=\"/src/tests/test.cf\"

> /etc/sendmail.pid The sendmail.pid file contains two lines of information. The first line is text representation of the pid of the current running daemon. The second is a copy of the command line that was originally used to start sendmail. This file is handy for killing and restarting the daemon (see Section 4.1.1, "Daemon Mode (-bd)"). If BSD4_4 is defined, the default becomes /var/run/sendmail.pid; otherwise, the default is /etc/sendmail.pid. You can change this default (and you must if you intend to run a test daemon in parallel to the original), with the ENVDEF= of your Makefile:

> >     ENVDEF= -D_PATH_SENDMAILPID=\"/src/tests/test.pid\"

> Ordinarily, two daemons cannot run simultaneously on a single host. If you need to run a second daemon, you must change the port that it listens to with the `Port` parameter of the `DaemonPortOptions` (`O`) option (see Section 34.8.13). /etc/hosts Ordinarily, sendmail will first look for a service-switch (see Section 34.8.61) to see how it should look up the canonical names of hosts. If it finds one and if the service hosts is listed, it uses the techniques listed with the service-switch to look up its hosts. When a technique is files, sendmail reads the file named by _PATH_HOSTS to get its canonical information. Ordinarily, that file is called /etc/hosts. If that file is different or has been customized on your system, you can redefine the location like this:

> >     ENVDEF= -D_PATH_HOSTS=\"/etc/privatehosts\"

> In general, most other techniques are preferred over the linear parse of a hosts file. However, this file is useful in determining the canonical name of the local host. Note that the location of the hosts file can also be changed with the `HostsFile` option (see Section 34.8.30, HostsFile). /dev/kmem The sendmail program decides when to refuse connections and when to only queue mail on the basis of its perception of the machine load average. The process of determining that average is hugely complex and varies greatly from vendor to vendor. Three pathnames that may be used in determining the load are _PATH_KMEM, _PATH_LOADAVG, and _PATH_UNIX. These should need to be changed only in the rare event that you are porting sendmail to a previously unsupported platform. Read the file conf.c to see the complex way they are presently used. Also see Table 18.6 to see how to use these to find the load average. /etc/shells A user is not allowed to run programs from a .forward file unless that user has a valid login shell (see Section 25.7.4, "Piping Through Programs"). Nor is a user allowed to save mail directly to files without a valid shell. To determine whether the login shell is valid, sendmail calls getusershell(3). If sendmail was defined without HASGETUSERSHELL defined (see Table 18.4), it instead tries to look up the shell in the /etc/shells file. If that file cannot be opened, sendmail gets valid shell names from an internal list called `DefaultUserShells` that is defined in conf.c. This _PATH_SHELLS definition can be used to change the location of the /etc/shells file. /usr/tmp In a panic situation (such as when sendmail cannot figure out how to deliver or bounce a mail message) the message is saved into the /usr/tmp/dead.letter file (see the `ErrorMode` (`e`) option Section 34.8.24, ErrorMode (e)). The _PATH_VARTMP definition is used to tune the location of the /usr/tmp directory. For some systems it is defined as /usr/tmp; for others it will need to be named /var/tmp. As distributed, it is undefined in all Makefiles, and it defaults to /usr/tmp.

> There is no debugging flag that will display the defaults for these file locations. If any are of concern, you should build sendmail yourself.

### 18.8.35 PICKY...

Make sendmail pickier

(tune with ENVDEF= in Makefile)

> The sendmail program can be made pickier by tuning its `PrivacyOptions` (`p`) option (see Section 34.8.47, PrivacyOptions (p)) or by defining two macros when compiling: PICKY_HELO_CHECK The SMTP HELO command is used to introduce the calling machine to the receiving machine. The form of that command is

> >     HELO calling host name here

> Note that HELO and EHLO are equivalent in this regard. Ordinarily, sendmail doesn't care what the calling host calls itself. All sendmail cares about is that this name is the canonical name of a machine. If you care whether the HELO hostname matches the real hostname of the calling machine, you can define PICKY_HELO_CHECK.

> >     ENVDEF= -DPICKY_HELO_CHECK

> With PICKY_HELO_CHECK defined, a mismatch (other than the local machine calling itself localhost) will result in this being logged:

> >     Host realname claimed to be heloname

> Note that this check is ordinarily turned off [15] because a large number of hosts on the Internet use a name that is different from their canonical name. PICKY_QF_NAME_CHECK The name of a queue file's control file is narrowly defined inside sendmail (see Section 23.2.1, "The Queue Identifier"). If only sendmail will be placing files into your queue, you might wish to turn on this macro for additional protection:

> > [15] Eric was getting complaints that the continual insertion of this warning was misleading and tended to cause people to ignore it entirely.

> >     ENVDEF= -DPICKY_QF_NAME_CHECK

> With PICKY_QF_NAME_CHECK defined, sendmail will log an error if the name of the `qf` file is incorrectly formed and will rename the `qf` file into a `Qf` file (see Section 23.3 for details of this process).

### 18.8.36 PSBUFSIZ

Size of prescan() buffer

(tune, edit conf.h)

> Whenever an address (including rules) is tokenized, it is stored in a single buffer, one token following the next with a zero-value byte separating them. The size of this buffer is defined by PSBUFSIZ. The default size is defined in conf.h as (MAXNAME + MAXATOM).

> In general, this definition should never be changed. If you start getting warning messages such as

> >     Address too long

> look elsewhere (such as rule sets) for the cause. You should consider changing the size of PSBUFSIZ only as a last resort.

### 18.8.37 QUEUE

Enable queueing

(tune, edit conf.h)

> If sendmail cannot immediately deliver a mail message, it places that message in a queue to await another try. The QUEUE definition causes queue-handling code to be included in sendmail. If queueing is not enabled and you need to queue, sendmail prints the following message and either bounces or discards the message:

> >     dropenvelope: queueup

> A word to the wise: Always define QUEUE. Even if you have only a pure UUCP machine, mail can fail (for a reason such as a full disk). Without queueing, such mail will bounce when instead it should be queued for a later try.

> The default is to always define QUEUE if NETINET or NETISO are defined; otherwise, QUEUE is undefined. There is no debugging flag to show whether QUEUE is defined, but the the `-bp` switch (see Section 23.4, "Printing the Queue") can be used to determine whether it is supported.

### 18.8.38 QUEUESEGSIZE

Amount to grow queue work list

(tune, edit conf.h)

> During a queue run, sendmail holds information in memory about all the files being processed. It does this so that it can sort them by priority for delivery. Beginning with V8.7 sendmail, there is no longer a limit (other than consuming all memory) on how many queued messages can be processed during any queue run. Prior to V8.7, that number was fixed by the constant QUEUESIZE. QUEUESIZE has been retired and replaced with QUEUESEGSIZE, which is defined in conf.h as:

> >     # define QUEUESEGSIZE   1000            /* increment for queue size */

> It should be changed only if your queue continually contains a huge number of messages. If you notice many messages like this being logged:

> >     grew WorkList for...

> you may need to modify QUEUESEGSIZE. Doing so requires that you edit conf.h and recompile.

> QUEUESEGSIZE can be traced with the `-d41` debugging switch (see Section 37.5.144, -d41.1).

### 18.8.39 SCANF

Support scanf(3) with F command

(tune with ENVDEF= in Makefile)

> The `F` configuration command (see Section 32.1.2, "The F Class Command") allows the specification of a scanf(3) style string to aid in parsing files (see Section 32.1.2.1, "scanf(3) variations"). In general this is not recommended because a misdesigned input file can cause sendmail to core dump. However, because of its popularity, it is enabled at compile time by default. If you don't need it, we recommend you exclude its support with ENVDEF= in Makefile.

> >     ENVDEF= -DSCANF=0

> >             disable scanf(3)

> The scanf(3) is used only in reading files into a class with the `F` configuration command. If you are running a precompiled version of sendmail, you can determine whether SCANF was included by using the `-d0.1` debugging switch (see Section 37.5.1).

### 18.8.40 SFS-TYPE

How to determine free disk space

(port, edit conf.h)

> The sendmail program can reject incoming mail messages if they are too large for the queueing disk. This ability is enabled by giving a positive, nonzero size to the `MinFreeBlocks` (`b`) option (see Section 34.8.40, MinFreeBlocks (b)). The method that sendmail uses to measure the free space on a disk varies from system to system. SFS_TYPE defines which of several methods sendmail will use. Those available are shown in Table 18.10.

> Table 18.10: Method to Determine Free Disk Space
> Define | Description
> --- | ---
> SFS_NONE | Your system has no way to determine the free space on a disk. This causes the `MinFreeBlocks` (`b`) option (see Section 34.8.40)to be ignored.
> SFS_USTAT | Your system uses the ustat(2) system call to get information about mounted file systems.
> SFS_4ARGS | Your system uses the four-argument form of the statfs(2) system call and <sys/statfs.h>. If you define this, you can also define SFS_BAVAIL as the field name for the statfs C language structure (by default, f_bavail).
> SFS_VFS | Your system uses the two-argument form of the statfs(2) system call and <sys/vfs.h>.
> SFS_MOUNT | Your system uses the two-argument form of the statfs(2) system call and <sys/mount.h>.
> SFS_STATFS | Your system uses the two-argument form of the statfs(2) system call and <sys/statfs.h>.
> SFS_STATVFS | Your system uses the statvfs(2) system call.

> In general, SFS_TYPE is correctly defined for all supported systems. You should need to modify it only if you are porting to a new system. To do so, you will need to edit conf.h.

> You can use the `-d4.80` debugging switch (see Section 37.5.19, -d4.80) to watch sendmail check for enough disk space. The only way to tell whether a precompiled version of sendmail has this ability is by setting the `MinFreeBlocks` option to a positive value and watching the `-d4.80` output. If `bavail=` in that output is always `-1`, no matter what, your support was defined as SFS_NONE.

### 18.8.41 SMTP

Enable SMTP

(tune with ENVDEF= in Makefile)

> If you are running sendmail as a daemon, you need to define SMTP to enable mail transfers. If you don't intend to run sendmail as a daemon, SMTP might not need to be defined. The default is that SMTP is automatically defined if either NETINET or NETISO is defined; otherwise, SMTP is undefined.

> SMTP support is recommended, even if sendmail is not running with network support or as a daemon. To take advantage of the new DSN protocol, future MUAs will talk to sendmail using SMTP over a pipe connection with the `-bs` command-line switch (see Section 36.7.11, -bs). The mh(1) suite of programs does that now. Delivery agents are also being designed with SMTP so that they can take advantage of DSN.

> You enable SMTP support with ENVDEF= in your Makefile:

> >     ENVDEF= -DSMTP=1

> If a precompiled sendmail lacks SMTP support, an attempt to use sendmail's `-bs` command line switch will result in this fatal error:

> >     I don't speak SMTP

> SMTP activity can be watched with the `-d18` and `-d19` debugging switches (see Section 37.5.65, -d19.1) and with the `-v` command-line switch (see Section 36.7.41, -v).

### 18.8.42 SMTPDEBUG

Enable remote debugging

(debug with ENVDEF= in Makefile)

> The sendmail program allows the developer to turn on debugging and to print the queue from any remote site. This capability is useful for solving occasional problems but opens a potentially wide security hole.

> In general, SMTPDEBUG should always be undefined. Later, when you become more expert with sendmail, you might want to have a standby version of sendmail ready (one with SMTPDEBUG defined), just in case you need it.

> There is no debugging switch that will let you know whether a precompiled version of sendmail had this defined. Instead, you must run it as a daemon, connect to it with telnet(1), and issue the SHOWQ SMTP command. If it displays the mail queue, then that precompiled sendmail was built with SMTPDEBUG defined, and you should not use it!

### 18.8.43 SMTPLINELIM

Default for obsolete F=L flag

(don’t change)

> Each delivery agent that is defined in the configuration file may or may not have an `L=` (Line length) equate (see Section 30.4.6, L=). If that equate is missing or if the value assigned to it is less than or equal to zero, and if the `F=L` delivery agent flag is set (see Section 30.8.29, F=L), the default value that is used becomes the value of SMTPLINELIM. Otherwise, the default value is 0. This logic is there to support old configuration files that use `F=L` in place of the newer `L=`.

> The default for SMTPLINELIM is 990 (defined in RFC821) and that value should not be changed. Rather, if you need a different line-length limit for a particular delivery agent, you should use the `L=` equate when defining it.

### 18.8.44 SOLARIS

Support Sun's Solaris 2.x

(port, edit conf.h)

> If compiling for a Sun Solaris machine, you will find this SOLARIS definition correctly defined for you in your Makefile:

> >     ENVDEF=    -DSOLARIS              Solaris 2.1 and 2.2
> >     ENVDEF=    -DSOLARIS=20300        Solaris 2.3
> >     ENVDEF=    -DSOLARIS=20400        Solaris 2.4
> >     ENVDEF=    -DSOLARIS=20500        Solaris 2.5
> >     ENVDEF=    -DSOLARIS=20501        Solaris 2.5.1

> Be sure to see src/READ_ME for several well-known pitfalls concerning Solaris.

### 18.8.45 SPT-TYPE

Adapt/exclude process title support

(port, edit conf.h)

> Whenever a program first begins to run, UNIX provides it with two arrays of information: its command-line arguments, and the environment under which it was run. When you run ps(1) to see what processes are doing, ps prints the command line that was used to run each program.

> To provide more useful information (such as current status or host connected to), sendmail saves its command line and environment, then periodically uses that system space to display its status. This ability provides a valuable tool for monitoring what each invocation of sendmail is doing.

> The method to display this information is correctly defined in conf.c for all supported systems. In the rare event that you need to port sendmail to another system, you may do so by defining SPT_TYPE in conf.h.

### 18.8.46 SUID-ROOT-FILES-OK

Allow root delivery to files

(debug with ENVDEF= in Makefile)

> When delivering to files, sendmail runs as the controlling user unless the suid or sgid bits of the file are set. If so, it runs as the owner of the file. A question arises when such files are root owned. Ordinarily, writing to suid and sgid root owned files as root is disallowed.

> If, for some reason, your site needs to allow delivery to root-owned files with sendmail running as root, you can enable this behavior with

> >     ENVDEF= -DSUID_ROOT_FILES_OK

> But be aware that you may open serious security holes on your system if you do this. We recommend that SUID_ROOT_FILES_OK never be defined, except as a temporary debugging technique. If you are running a precompiled sendmail binary, you can use the `-d0.1` debugging switch (see Section 37.5.1) to determine whether SUID_ROOT_FILES_OK was defined in it.

### 18.8.47 SYSLOG-BUFSIZE

Limit syslog(3) buffer size

(port, edit conf.h)

> The sendmail program logs errors, information, and debugging messages using the syslog(3) facility. By default, sendmail uses a 1024-byte buffer to assemble each message before dispatching it, but some systems don't accept a buffer this big. For such systems you can reduce the size of that buffer by defining SYSLOG_BUFSIZE with a new size:

> >     ENVDEF= -DSYSLOG_BUFSIZE=512

> >              reduce syslog(3)'s buffer size

> First, note that SYSLOG_BUFSIZE is correctly set in conf.h and Makefiles/* for all supported systems. Second, note that setting the buffer to fewer than 256 bytes causes sendmail to log many more smaller messages (each item of information on a separate syslog(3) line). If SYSLOG_BUFSIZE is less than 89, some logging information will be lost.

> SYSLOG_BUFSIZE has an effect only if sendmail was compiled with LOG defined, (see Section 18.8.16), and if the `LogLevel` (`L`) option (see Section 34.8.33) is set to 6 or more, and if your syslog.conf(5) file is configured to log mail messages at LOG_INFO and above (see Section 26.1, "Logging with syslog"). If you are running a precompiled version of sendmail, there is no way to determine the setting of SYSLOG_BUFSIZE.

### 18.8.48 SYSTEM5

Support SysV-derived machines

(port, edit conf.h)

> If you are compiling sendmail on a SysVR4-derived machine, you should define SYSTEM5. This automatically causes the correct SysV support to be included. For all systems that require SYSTEM5 to be defined, it is already correctly defined in conf.h.

> If you suspect that you need to define SYSTEM5 when porting to a new system, you should also investigate SYS5SIGNALS and SYS5SETPGRP in conf.h and READ_ME. If you are running a precompiled version of sendmail, you can use the `-d0.10` debugging switch (see Section 37.5.3) to discover whether SYSTEM5 or SYS5SETPGRP were defined.

### 18.8.49 TCPWRAPPERS

Use libwrap.a for connects

(tune with ENVDEF= in Makefile)

> Beginning with V8.8 sendmail, it is now possible to use the libwrap.a library to validate incoming SMTP connections. To enable this ability, you need to define TCPWRAPPERS and arrange for the libwrap.a library to be included in your Makefile:

> >     ENVDEF= -DTCPWRAPPERS
> >     LIBS= -lwrap

> See src/README and Section 22.4.1, "Accept/Reject Connections via libwrap.a" for additional information.

### 18.8.50 TOBUFSIZE

Set buffer for recipient list

(tune, edit conf.h)

> For each delivery of one or more recipients to a single delivery agent, sendmail issues a summary of delivery through syslog(3). When logged, the recipient part of the message looks like this:

> >     to=recipients

> Here, recipients is a comma-separated list of recipients. The maximum number of characters in this list is determined by TOBUFSIZE. That limit is intended to prevent the internal syslog(3) buffer from overflowing. On machines with older versions of syslog(3) you may need to reduce the size of TOBUFSIZE in conf.h. In general, TOBUFSIZE is correctly defined for all currently supported systems. You should need to change it only if porting to a new system.

> Note that one side effect of TOBUFSIZE is that it also limits the total number of recipients that can be delivered at once. If you need to increase that limit (and if you have a robust version of syslog), you can experiment by cautiously increasing TOBUFSIZE.

### 18.8.51 TRUST-POPEN

Allow use of popen(3)

(debug with ENVDEF= in Makefile)

> The sendmail program uses the uname(2) system call to determine the UUCP name of the local host. If your machine lacks the uname(2) call (if HASUNAME was not defined), sendmail attempts to emulate uname(2) with its own internal routine. That internal routine first tries to read the /etc/whoami file. If that fails, it then tries to parse /usr/include/whoami.h. Finally, if that fails and if TRUST_POPEN is defined, sendmail executes the following command to get the UUCP name:

> >     popen("uuname -l", "r")

> The result (no matter how it was obtained) is then placed into the `$k` macro (see Section 31.10.21, $k).

> In general, you should never define TRUST_POPEN. The popen(3) call presents a huge security risk. If your system lacks uname(2) and is unable to set its UUCP name, consider hard-coding that name in the configuration file:

> >     Dkuucpname

> You may wish to define TRUST_POPEN temporarily to see whether that causes your UUCP name to be found. Once that is done, undefine it for your final release of sendmail.

> There is no debugging switch that will tell you whether TRUST_POPEN was defined in a precompiled version of sendmail. If that binary is not stripped, you can use nm(1) to check for popen(3) support:

> >     % nm sendmail | grep popen
> >     00058bc8 T _popen                       found, so TRUST_POPEN was defined

> If sendmail is stripped, you can still run strings(1) in order to check for the actual command:

> >     % strings sendmail | grep "uname -l"
> >     uuname -l                               found, so TRUST_POPEN was defined

> In either event you should contact your vendor and ask for this security risk to be removed.

### 18.8.52 TTYNAME

Set $y to tty name (obsolete)

(debug with ENVDEF= in Makefile)

> The `$y` macro (see Section 31.10.44, $y) is intended to hold as its value the base name of the controlling tty device (if there is one). On BSD-derived systems this is a name like the following, but with the `/dev/` prefix removed:

> >     /dev/tty04

> Defining TTYNAME enables sendmail to put this information into `$y`:

> >     ENVDEF= -DTTYNAME

> Note that TTYNAME is useful only for debugging sendmail. The sendmail program does not itself use `$y` for anything. Also note that defining TTYNAME requires that your system support the ttyname(2) system call. If you are running a precompiled version of sendmail, you can determine whether TTYNAME was defined by sending mail with the `-d35.9` debugging switch (see Section 37.5.120, -d35.9) and watching for `$y` to be defined:

> >     define(y as ttyp1)

### 18.8.53 UDB-DEFAULT-SPEC

Default User Database location

(tune with DBMDEF= in Makefile)

> If you wish to define a default location for the User Database that will take effect if the `UserDatabaseSpec` (`U`) option (see Section 34.8.75, UserDatabaseSpec (U)) is missing, you can define it, for example, like this:

> >     DBMDEF= -DNEWDB -DUDB_DEFAULT_SPEC=\"/var/db/userdb.db\"

> The backslashed quotation marks are necessary to pass the path to sendmail as a string.

### 18.8.54 USERDB

Support the User Database

(tune with DBMDEF= in Makefile)

> The User Database (see Section 33.5) is code inside sendmail that allows sender and recipient addresses to be rewritten under the control of an external database. This code is automatically included in sendmail when you define NEWDB or HESIOD:

> >     DBMDEF= -DNEWDB           automatically include User Database code
> >     DBMDEF= -DHESIOD          automatically include User Database code

> If you don't want to include support for the User Database, you need to specifically turn it off by setting USERDB to 0:

> >     DBMDEF= -DNEWDB -DUSERDB=0
> >     DBMDEF= -DHESIOD -DUSERDB=0

> See UDB_DEFAULT_SPEC for a method to set a default for the database location. If you are running a precompiled sendmail binary, you may use the `-d0.1` switch (see Section 37.5.1) to determine whether USERDB support is included.

### 18.8.55 USESETEUID

Support seteuid(2) identity changes

(port, edit conf.h)

> .SS "seteuid routine" To perform most kinds of delivery in a safe manner, sendmail must be able to change its root identity to that of another user, deliver as that user, and then restore its identity to root. The preferred method for doing this is with the Posix 1 seteuid(2) routine. To determine whether your system correctly supports this routine, compile and run the program test/t_seteuid.c. The compiled binary must be suid-root and must be executed by an ordinary user.

> >     # cc t_seteuid.c
> >     # chmod u+s a.out
> >     # suspend
> >     % a.out
> >     ... lots of output here
> >     This system cannot use seteuid

> Here the output shows failure, so you do not have seteuid(2) support. Beginning with V8.8, a.out prints the following on success:

> >     It is safe to define USESETEUID on this system

> If the output had not shown failure or had shown success (if you had usable seteuid(2) support), you could take advantage of that support by defining USESETEUID in conf.h. In general, USESETEUID is correctly defined for all systems that can take advantage of this seteuid support.

> If seteuid(2) failed, you need to investigate using setreuid(2) instead:

> >     # cc t_setreuid.c
> >     # chmod u+s a.out
> >     # suspend
> >     % a.out
> >     initial uids (should be 678/0): r/euid=678/0
> >     after setreuid(0, 1) (should be 0/1): r/euid=0/1
> >     after setreuid(-1, 0) (should be 0/0): r/euid=0/0
> >     after setreuid(realuid, 0) (should be 678/0): r/euid=678/0

> >     after setreuid(0, 2) (should be 0/2): r/euid=0/2
> >     after setreuid(-1, 0) (should be 0/0): r/euid=0/0
> >     after setreuid(realuid, 0) (should be 678/0): r/euid=678/0

> >     It is safe to define HASSETREUID on this system

> Here, the test succeeded (no failure message was printed prior to V8.8). If your system can use setreuid(2), you can take advantage of it by defining HASSETREUID in conf.h.

> No matter which you define, be sure to read src/READ_ME for possible pitfalls. Note that HASSETREUID and USESETEUID are correctly defined for all currently supported systems. You need to define one only if you are porting sendmail to a completely new system.

> If you are running a precompiled sendmail binary, you can use the `-d0.1` switch (see Section 37.5.1) to discover whether HASSETREUID or USESETEUID support is included.

### 18.8.56 WILDCARD-SHELL

Redefine wildcard shell

(debug, edit conf.c)

> Ordinarily, sendmail prohibits ordinary users from running programs from inside their ~./forward files unless they have a valid login shell. This restriction is in place to prevent ordinary users from running arbitrary programs on a main mail server. Some sites prefer to allow users to run arbitrary programs despite the restriction about logging into the mail server. At such sites, one can bypass this restriction by placing the special string

> >     /SENDMAIL/ANY/SHELL/

> in the /etc/shells file. If, for some reason, you need to use a different string, you may do so by redefining WILDCARD_SHELL in conf.c.

> If you enable arbitrary programs you should also implement the sendmail restricted shell smrsh (see Section 22.8.2, "The smrsh Program").

### 18.8.57 XDEBUG

Support sanity checks

(debug with ENVDEF= in Makefile)

> In past releases of sendmail, changes in file descriptors and other key variables have sometimes occurred for reasons that remain a mystery to this day. Small "sanity checks" have been included in the code to discover such anomalies, should they happen again. To exclude these checks, redefine XDEBUG to 0:

> >     ENVDEF= -DXDEBUG=0

> Generally, however, XDEBUG should always remain enabled. It adds only a microscopic amount of overhead to sendmail and helps to certify sendmail's rational behavior.

> If sendmail's notion of who it is (as defined by the `$j` macro; see Section 31.10.20, $j) gets trashed by losing all its dots, sendmail will log the following at LOG_ALERT if XDEBUG is defined, dump its state (see Section 26.3.3, "SIGUSR1 Dump States"), and abort(3):

> >     daemon process $j lost dot; see syslog

> At startup the value in the `$j` macro (see Section 31.10.20) is appended to the class `w` (see Section 32.5.8, $=w). If sendmail is compiled with XDEBUG, it periodically checks to make sure that `$j` is still listed in class `w`. If `$j` should vanish, sendmail will log the following at LOG_ALERT, dump its state (see Section 26.3.3), and abort(3):

> >     daemon process doesn't have $j in $=w; see syslog

> With XDEBUG defined, sendmail periodically checks to see whether its standard I/O file descriptors have gotten clobbered. If so, it logs the following and tries to recover by connecting it to /dev/null:

> >     where: fd which not open

> Here, `where` will reflect the internal subroutine name and arguments that led to the check, and `which` will be the bad file descriptor number.

> If you are running a precompiled sendmail binary, you can use the `-d0.1` switch (see Section 37.5.1) to determine whether XDEBUG support is included.

18.7 Pitfalls |  | 19. V8 m4 Configuration