Vernon Schryver
Tue Jan 13 18:50:33 UTC 2004

> From: Sven Willenberger 
> Another option here would be to use the -a IGNORE argument to dccm and
> then use something like procmail or maildrop to filter headers and
> discard bulk email by default, and using user-specific rules for those
> accounts who are to ignore the bulk setting.

That is a solution, but it should be avoided in favor of rejecting as
much spam as possible during the SMTP transaction instead of after.
If you delay filtering until after the SMTP transaction has ended,
then the only indication the sender can receive is a "bounce" or DSN.
A bounce involves a second mail message and so is subject to all of the
potential problems of any mail message.  Those problems are increased
when spam is involved.  For example, the bounce might be rejected by
the SMTP server of the sender of the original message because of some
spam taint (not necessarily related to anything the DCC knows about).

Then there are the problems of sending bounces to the supposed senders
of spam.  A lot of spam currently has bogus sender addresses.  Rejecting
mail after the end of the SMTP transaction risks sending the "bounce"
to an innocent victim of a "joe job."  A few people have been flooded
with such bounces.

On the other hand, if your system rejects mail during the SMTP transaction,
the responsibility for notifying the sender is on the sender's system.
If the sender is the spammer, then the worst that might happen is that
the spammer will "unsubscribe" a target address.  

Vernon Schryver

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