Email filtering with MIMEDefang

This presentation will show how XS4ALL Internet is using MIMEDefang
(http://www.mimedefang.org/) to filter e-mail. As the mimedefang
webpage explains: "MIMEDefang is a framework for filtering e-mail. It
uses Sendmail's "Milter" API, some C glue code, and some Perl code to
let you write high-performance mail filters in Perl."

This talk will give a short introduction to mimedefang and the
surrounding mail architecture, and will focus on the filters we
developed at XS4ALL to filter our mail flow.

Specifically, we have first developed a framework to make the perl
filters modular, which allows for easier testing and maintenance of
the code. We have then added several modular components of the filter,
for example to check against DNS blacklists, to verify sending domains
beyond what sendmail does by default, to check for quota exceeded situations
early in the SMTP conversation, to do reliable virus scanning, and last
but not least to do spamfiltering using spamassassin.