This installation of Exim includes Exiscan content scanning support,
from http://duncanthrax.net/exiscan-acl/, which is documented in
%%DOCSDIR%%/exiscan-acl-spec.txt.  The ports tree
includes various content scanners that might be useful, e.g.
mail/p5-Mail-SpamAssassin and security/clamav.

Notes for enabling malware scanning with the excellent clamd scanner
are in %%DOCSDIR%%/POST-INSTALL-NOTES.clamd.

When Exiscan is actually enabled in the Exim configure file, great
care should be taken to test upgrades, since Exiscan updates tend
to not maintain backward compatibility.