The following instructions describe how to integrate SpamAssassin into a number of popular MTAs. Once SpamAssassin has been integrated into the MTA, basic MTA configuration should be tested and the user should confirm that SpamAssassin headers are being added to emails.
There are several methods of integrating SpamAssassin into sendmail. Sendmail has a plug-in architecture known as milter. There are several milters available for use with SpamAssassin. Here we will discuss only MIMEDefang.
To use MIMEDefang, milter support must be built into sendmail. For sendmail versions 8.13 onwards, this is the default. If sendmail was supplied in a package, for example RPM, then the distributor may or may not have included this.
To test for milter support, issue the following command and examine the results:
# /usr/sbin/sendmail -bt -d0.1 </dev/null
Version 8.12.10
Compiled with: DNSMAP LOG MAP_REGEX MATCHGECOS MILTER MIME7TO8MIME8TO7NAMED_BIND...