A sendmail.m4 file for vstout at the Virtual Brewery is shown below. vstout uses SMTP to talk to all hosts on the Brewery's LAN, and sends all mail for other destinations to moria, its Internet relay host, via UUCP.
dnl #------------------ SAMPLE SENDMAIL.M4 FILE ------------------
dnl # (the string 'dnl' is the m4 equivalent of commenting out a line)
dnl # you generally don't want to override LIBDIR from the compiled in paths
dnl #define(LIBDIR,/usr/local/lib/mail)dnl # where all support files go
define(LOCAL_MAILER_DEF, mailers.linux)dnl # mailer for local delivery
define(POSTMASTERBOUNCE)dnl # postmaster gets bounces
define(PSEUDODOMAINS, BITNET UUCP)dnl # don't try DNS on these
dnl #-------------------------------------------------------------
dnl #
define(PSEUDONYMS, vstout.vbrew.com vstout.UUCP vbrew.com)
dnl # names we're known by
define(DEFAULT_HOST, vstout.vbrew.com)dnl # our primary 'name' for mail
define(UUCPNAME, vstout)dnl # our uucp name
dnl #
dnl #-------------------------------------------------------------
dnl #
define(UUCPNODES, |uuname|sort|uniq)dnl # our uucp neighbors
define(BANGIMPLIESUUCP)dnl # make certain that uucp
define(BANGONLYUUCP)dnl # mail is treated correctly
define(RELAY_HOST, moria)dnl # our smart relay host
define(RELAY_MAILER, UUCP-A)dnl # we reach moria via uucp
dnl #
dnl #--------------------------------------------------------------------
dnl #
dnl # the various dbm lookup tables
dnl #
define(ALIASES, LIBDIR/aliases)dnl # system aliases
define(DOMAINTABLE, LIBDIR/domaintable)dnl # domainize hosts
define(PATHTABLE, LIBDIR/pathtable)dnl # paths database
define(GENERICFROM, LIBDIR/generics)dnl # generic from addresses
define(MAILERTABLE, LIBDIR/mailertable)dnl # mailers per host or domain
define(UUCPXTABLE, LIBDIR/uucpxtable)dnl # paths to hosts we feed
define(UUCPRELAYS, LIBDIR/uucprelays)dnl # short-circuit paths
dnl #
dnl #--------------------------------------------------------------------
dnl #
dnl # include the 'real' code that makes it all work
dnl # (provided with the source code)
dnl #
include(Sendmail.mc)dnl # REQUIRED ENTRY !!!
dnl #
dnl #------------ END OF SAMPLE SENDMAIL.M4 FILE -------