[Mimedefang] Interesting anti-HTML filter side-effect

[David F. Skoll]

I just noticed something quite interesting in my logs.

I have rules that reject HTML messages under certain circumstances.
Basically, if one of these conditions holds:

1) The recipient is in one of a handful of domains I host for friends
and relatives, or

2) The sender is one of a handful of mailing list senders, or

3) The domain "roaringpenguin.com" appears in the To: or Cc: header,

then I allow HTML messages in.  If none of those conditions holds,
then I bounce HTML.  I find this to be a very effective anti-spam technique.

I *also* found that it bounced that latest virus, whatever it is
called.  Sample log entry:

Sep 18 21:54:24 www mimedefang.pl[1072]: h8J1sNtU011922 from
    <obscure at for.privacy> via 10.0.0.0 (obscure.for.privacy)
    re: (Current Net Critical Upgrade) bounced because of HTML

I think if we can convince people that HTML mail is dangerous, we'll
go a long way to making e-mail usable again, and a long way to limiting
the creative techniques available to spammers.

Regards,

David.