Vernon Schryver <vjs(_at_)calcite(_dot_)rhyolite(_dot_)com> wrote:
I know of many millions of spam that are filtred during the DATA command
every day, and I don't claim to know about any really big sites.
The only problems are:
- local administrative choices that keep bastion SMTP servers ignorant
of per-user filter preferences
This is a feature, not a problem. If the end user wants a filtering
process individualized that much, s/he should choose to use a SMTP
server which agrees to do so.
- filtering at the DATA command requires either (1) rejecting for
all or no targets or (2) accepting for all targets and siliently
discarding the message for those targets that want it filtered.
Alternatively, the receiving SMTP server could reject any multiply-
addressed email.
Is it actually that unreasonable to apply the most-restrictive
filtering rules in the case of multiply-addressed email?
(Silently discarding _is_ a bad idea, when done by the SMTP server
itself. IMHO, it's better to mark for later discard -- which actually
could be done in such a way as to mark only for those recipients who
requested the more restrictive filtering.)
In theory the second problem could be fixed if the DATA command could
accept a vector of 250-OK/4yz-try-later/5yz-fatal responses, one for
each target named with a Rcpt_To command. In practice the spam problem
will be solved one way or another long before such a protocol change
would be sufficiently widely deployed to matter.
Agreed: that radical a change in SMTP wouldn't percolate through
quickly enough.
--
John Leslie <john(_at_)jlc(_dot_)net>