SPAM Bounce

Richard Westlake r.westlake at MAIL.CRYST.BBK.AC.UK
Thu Mar 20 14:48:31 GMT 2003


Sorry it this has already been covered by I only read the list in digest
form.

Steffan
Don't assume that people read or understand the bounce/failure messages
from a mail system, or even that the bounce message  text ever get to the
sender. Some mail clients seem to filter out the bounce message and
replace it all with a really useful message like "Protocol error". :-(

I have users who don't even read  the text in the "Sorry we haven't been
able to deliver you message for the last four hours, but we will keep
trying", they forward it to support assume that our system is broken.

In late 1999, after loud complaints from our users we started blocking
email connections from open relays, this greatly reduced the amount of
spam. We returned an error message with a URL for more information and I
assumed that people would either look at the URL and understand the
problem or ask there local computer support what it meant, after all some
of our users would forward to support the "Sorry we haven't been able to
deliver you message for the last four hours, but we will keep trying"
messages. What we found was that most people simply ignored the bounce,
resent several times and then gave up. Sometimes if we were lucky they
would phone the recipient and fax us a copy of the bounce message, that
was when we discovered that some mail clients or systems didn't show the
bounce text only a stupid message like "Protocol error".

We had to switch off most of the blocking in January 2000 as the users who
complained loudest about the spam before the blocking then complained just
as loud if not louder about the blocking, they sill complain about the
spam. :-(

At the time I was rather surprised by some of the people running open
relays, including mail hubs for large organisations, which should have
known better. Hopefully things have since improved, I know that JANET (the
UK academic network) now has a zero tolerance policy on open relays.

After Jan 2000 we only blocked know dial up addresses from the MAPS DUL
however recently we switched to the MAPS RBL+ via the JANET. No complaints
about the blocking so far, but we are still getting a lot of spam some of
which is tagged by SpamAssassin.

We use the Dynamic Relay Authorization Control (DRAC)
http://mail.cc.umanitoba.ca/drac/ software to allow our users to send mail
from dial up connections, which would normally be locked by the dialup
black hole lists.
DRAC  provides IMAP(or pop) login before SMTP relaying.

All the best


Richard Westlake

School of Crystallography, Birkbeck College, Malet Street, London WC1E 7HX
Tel: 020-7631-6859
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               Truth endures but spelling changes    --  Anon.
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