Way back when there was a time when my mail was handled by sendmail, procmail and UW-imapd. I came up with a procmail recipe that would lookup sender ip addresses in various DNSBL services.

There are not a lot of instructions for this. Basically extract the archive in a convenient location. This could be somewhere in a users directory or in /etc for a system wide installation. Include dnsbl in /etc/procmailrc or some other procmail recipe. It would be a good idea to edit the TRUSTED_HOSTS parameter in dnsbl, this is really essential actually.

Download:

procmail-dnsbl.tar.gz

Or have a look at the files in the distribution without downloading the archive:

• dnsbl
• dnsbl_ip
• dnsbl_test
• trimmbox

One final comment, it’s been a long time ago that I wrote this. I probably did a lot of research. I remember this being quite the procmail learning experience. I probably skimmed code fragments here and there to put this together, but I really don’t remember so I can’t give credit if credit is due.