Sendmail::AccessDB provides an API for users of
Sendmail::Milter to easily determine if a recipient is
a "willing recipient" of spam, or if a particular site
has been explicitly whitelisted, so that mail from
there is not blocked. It also allows generic lookups.
Hunnypot is a SMTP server-like program that harvests information about machines on the Internet that are sending spam and/or worms. It stores its findings in a SQL database, which makes it trivial to start rejecting SMTP connections from these spammers.
PyWebMail is a Python library and POP3 gateway
that allows you to work with webmail servers as if
they were POP3 or IMAP mail servers. Currently,
support for Mail.Com, Yahoo! Mail, Gmail,
Netscape, HotMail and some minor servers is
finished.