At 12:00 22/01/2001 -0600, Gwinn, Allen wrote:
One approach that I've thought casually revolves around a feature in
Sendmail that would open an SMTP connection back to the sending host
(assuming the sender had smtp services) and test it for relaying mail back
to you. You could then accept or reject mail from that host based on the
finding. Not that I've thought about it in depth, but you could hash status
for incoming mail hosts after probing them. But this would encourage people
to close host relays.
Some people do this now.
And sometimes, they bounce mail because of transient failures; DNS timeouts
when looking up the sender's domain, for instance.
(Other times, they bounce mail because I forgot to configure the envelope
sender as a deliverable address; I deserve that :-)
(The Linux Counter Project, http://counter.li.org/, is currently sending
out mail to all participants who registered two years or more ago, to
verify that they are still around, and still want to be listed. I learned a
LOT about how to check for deliverable mails....)
--
Harald Tveit Alvestrand, alvestrand(_at_)cisco(_dot_)com
+47 41 44 29 94
Personal email: Harald(_at_)Alvestrand(_dot_)no