Our customers publish and check SPF (rejecting mail on the 3 strikes and
yer out principle). They also do bayesian spam filtering. A user (who
shall remain nameless) at one such customer did the following:
1) opted out of spam filtering on the company MTA.
2) forwarded her company mail to her AOL mailbox. The company
has squirrelmail, but she likes AOL better. SPF blocks some forgeries, but
lots of spam is still forwarded to AOL.
3) used the AOL email client to mark the spam and train the AOL spam filter.
4) AOL gives demerits to the sending IP based on number of messages marked
as spam by AOL users: http://postmaster.info.aol.com/errors/421sdit1.html
5) AOL now blocks all email from this customers MTA to AOL.
I actually think that AOLs policy is reasonable. The actions of the user
were not - but I see why she did not understand the consequences of
using the AOL spam filter vs. the company spam filter. She figured they
were both spam filter applications, and she liked the AOL application better.
Anyway, we have banned user configured email forwarding for the time
being. We may reenable it provided they are also using the local
spam filter.
COMPLAINT:
One thing that AOL screwed up on: they drop the connection rather than
issuing a 5xx status. The end user sees "connection dropped, will retry
for the next 12 days" and there is no indication of why there is a
problem. AOL issues a 2xx status, with human readable text providing
the URL above and then drops the connection. This is very wrong.
They should issue a 5xx status so that the MTA knows to pass the
error on to the user.
--
Stuart D. Gathman <stuart(_at_)bmsi(_dot_)com>
Business Management Systems Inc. Phone: 703 591-0911 Fax: 703 591-6154
"Confutatis maledictis, flamis acribus addictis" - background song for
a Microsoft sponsored "Where do you want to go from here?" commercial.