I'm currently using maildrop to do delivery, because I like to use it's xfilter to pipe through spamc.
I don't see a similar option for dovecot's deliver. Is there something? It would be nice to use deliver, since I use dovecot for reading mail.
why not do spam filtering at MTA level? works very well here.
I prefer doing spam filtering at the SMTP/gateway level - drastically reduces the load on my postfix server. Even though Postfix's header checks are very effective, ASSP is even better, and getting better every day. Fritz is also in the process of integrating ClamAV back into it, so it will even handle the virus scanning too. ASSP just plain rocks!
The development is very active, but you have to join the USER mail list (the dev list is not nearly as active) to see that. The sourceforge page lags behind quite a bit, but at least was recently updated to reflect the massive (unofficial) changes that had been implemented by Fritz. That has now been rectified, and Fritz is an official dev for ASSP.
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Best regards,
Charles