I use Mail::Audit to filter all my mail. It gives me the flexibility of Perl, allowing me to do a great many things that would be impossible with procmail alone; For example, I create an XML file that lists the subject and sender of the last mail to London.pm. I have special email addresses that I can forward messages to that kill all messages either to or from a particular address forevermore. Finally I have temporary email addresses - address that only work for one day and one day only that automatically get filtered off to /dev/null after that - very useful for site registration.

Foo.