Greylisting, (anti)spam, etc
I've been working way too much lately, but at least I've taken the time to install a new spam filter on my mail server. It was actually only a very small patch to the qmail source that was needed to get it to filter mail through policyd. Policyd is primarily made for Postfix, but seems to work great with qmail too. That puts an end to my own greylisting project, which only greylisted on source-IP/24. The "greysmtpd" app was working as it should but there were too many spammers in the world to make it effective enough.
http://home.graffiti.net/feizhou:graffiti.net/patches.html
Combination big-todo and ext-todo patch for qmail. If you have a high volume qmail server that has very high injection rates, then this patch gives both the benefits of ext-todo and big-todo.
qmail: the Internet’s MTA of choice
qmail is a secure, reliable, efficient, simple message transfer agent. It is designed for typical Internet-connected UNIX hosts.