Strong Anti-Email Spam Protection In Place…

We are tweaking our postfix servers to offer maximum spam protection upfront with helo checks, header checks, blacklist checks, RBL’s and more. So far my daily spam count has dropped from about 3000-7000 spams / day to about 15-35 spams per day. It should drop even more as I added more RBL to my list (see below for updates).

One of the check which tested for valid HELO domain was causing problems with some legitimate senders like PayPal and few clients. You may be one of them too. I have removed this particular HELO restriction for now and opted for more RBL’s. The two frontline RBL’s I am using are spamcop & spamhaus. They along with sorbs are worth their weight in gold.

If you don’t receive any response from me, please send your email again. You may have been inadvertently blocked by our spam protection measures.

I am also thinking of adding greylisting & maybe spf checks. Any suggestions? Any idea on compliance of SPF & DomainKeys with major providers?
Note: We do provide SPF records on outbound mails but haven’t added DomainKeys yet.

BTW: Does CLAMAV serve any practical purpose on Linux?

Update: After my last set of postfix changes email spam have dropped to zero. I am now checking to see if there are any false positives.