29,148 messages : Host sending mail was in our local blocklist
How many entries? Does it just keep growing? We have a local one too,
and every so often correlate it with the public RBLs so as to not
duplicate the check and overhead.
They expire in 2 weeks. They should make it into a public RBL by
that time. Maybe it should even be shorter.
46,037 -------- : Sender address was a user unknown @columbia.edu
done by Sendmail, local ruleset
Sender address? Are you talking about protection from dictionary
attacks, like a...@columbia.edu, b...@... etc?
If the sender claims to be a...@columbia.edu, then we can verify whether
the localpart aaa exists. Our own domain is the only one for which we
can check localpart, of course. If it does not exist, goodbye.
It's not 100% spam. A few are legit users who mistyped the address in
a mail client configuration. It's worthwhile giving them an error too,
so they'll know about it.
Joseph Brennan
Columbia University Information Technology
