Делай связку Spamassasin-Sendmail с помощью milter-spamc
сейчас он платный, но старые версии халявные если не найдешь я вышлю
сам milter работает стабильно, я его еще доработал и связал с mysql
Выдержка из хелпа:-a email copy all mail to email address
-A always add the X-Spam-Report: header report of rules triggered
-b email copy junk mail to email address
-B email redirect junk mail to email address
-c email copy clean mail to email address
-C check for spam only, disable X-Spam-Report: header completely
-d excess discard spam messages that exceed the threshold by N
-f cf pathname of sendmail.cf file for access database whitelists
-F format redirect junk mail to reformated recipient addresses
-h this usage summary
-H host spamd host name or IP
-K kilo how many KB to pass to SpamAssassin, 64 default, 0 unlimited
-l limit limit number of untrusted recipients per message
-p discard instead of reject if Precedence is list or lower
-P port spamd port address, -1 to disable spamd filtering
-r excess reject spam that exceeds the threshold by N, overrides delivery
-R excess reject spam that exceeds the threshold by N, allow delivery
-s tag spam subject tag
-S append the spam score to the spam subject tag
-t timeout sendmail/milter I/O timeout in seconds, 0 indefinite
-T timeout milter/spamd I/O timeout in seconds, 0 indefinite
-u user default user account to process messages with
-U user force message processing with this user account
-v detail comma separated list of what to write to the mail log:
0, all, info, trace, parse, debug, dialog, state, dns
cache, database, socket-fd, socket-all, libmilter
