I use CanIt Pro, a spam filter based on MIMEDefang, which uses the
sendmail milter API.  Before I placed listserv behind the filter, I used
to see a lot of rejected posting messages being sent out, with many being
returned as undeliverable.

I was wondering if it would be possible for Listserv to at least check for
permission to post during the incoming SMTP connection, and perhaps 5xx
reject the message after the RCPT TO: if the sender is not allowed to post
to the list.  The error could read something like

  554 5.7.1 Sender not authorized to post to <LISTNAME>

By rejecting messages at the SMTP level, Listserv would not have to
generate a message to someone that may or may not exist.  The downside is
you wouldn't be able to send much text, but my experience has been that
users (and tech support staff) don't read the text of the message anyways.
 Another problem may be presented by certain broken mail systems (cough
cough exchange cough cough) that don't always return the SMTP error
messages.  Good logging would at least help the site manager troubleshoot
the issue.

Would this be a good idea?  Even possible??

--
The Kool-Aid from Redmond is powerful stuff.  -- Gregg Eldred


William Brown
Web Development & Messaging Services
Technology Services, WNYRIC, Erie 1 BOCES
(716)821-7285