I'm finding it more and more difficult running my own mailserver and am curious if anyone else has run into the same problems (and solved them). I spend a ton of effort fighting spam and have installed several systems to deal with the deluge. Some work well, others don't. Here are the current list of problems: 1) Some of my outgoing mail gets rejected by spam fighting systems - just regular mail from me to someone else (ie. NOT Spam). I'm not sure what the criteria are - probably because they come from a Non-ISP mailserver. 2) My system is set up to subject incoming mail to a 20 minute delay or "greylist" (google "milter-greylist" for details). Some mail servers consider that delay a "permanent failure" and the message is never delivered - the sender receives a bounce message. 3) If I try to use my ISP's mailservers, even one or two "spam" emails put me on their "blacklist" and all mail gets rejected. False negatives still happen - but very seldom. In my spam battle, I use: Milter-Greylist with a 20 minute delay - that eliminates a huge number of spam - saves tons of cycles for the next step Mailscanner with Clamav and Spamassassin - spamassassin is almost useless for "image" spam - marking an email as spam and forwarding is pointless if it's going to another mailserver Sendmail is configured to NOT forward mail except for domains I host. Several DNS Blacklists (sendmail) - getting less reliable My system rejects thousands of emails per day through the "grey-list", accepts several 100's of emails of which perhaps 30% spam. Spam emails are marked as "possibly spam" and delivered intact and some are marked as "certainly spam" and quarantined with notification (and an option to retrieve them). -- This message has been scanned for viruses and dangerous content by Avantel Systems, and is believed to be clean.