[Mimedefang] regex filter unwanted words

[Richard Laager]

On Tue, 2007-01-23 at 08:51 -0500, WBrown at e1b.org wrote:
> John Rudd wrote on 01/22/2007 06:17:48 PM:
> 
> > As many as you can fit.  But I would be very careful about it.  Plus, I 
> > would make sure to use "\b" around the words, so that you're not getting 
> 
> > sub-string matches.  For example:
> > 
> > \bsex\b  will match "sex" but not match "Wesex".
> 
> I can't second this strongly enough!  I had a very *IRATE* user 
> complaining about not receiving email from his boss.  Turns out he had 
> created a rule in his mail client to block a certain four letter word and 
> forgot about it.  The problem started when he added his title "Programmer 
> Analyst" to his signature block and he stopped getting replies to his 
> messages.

The best one I ever ran into went like this: A user calls in to complain
that large attachments are being blocked. Smaller attachments work, but
at some unknown point when the messages become "too big", they are
blocked. We eventually narrowed it down to a filter on "sex" (as well as
some others for 4-letter words) anywhere in the message body. My theory
was that as messages with attachments got larger and larger, the
probability of them containing "sex" in the base-64 encoded data
approached one. We disabled that filter rule, and everything worked
great again.

Richard