[Mimedefang] Whitelisting Outbound E-Mail Addresses

[Matthew.van.Eerde at hbinc.com]

> From: David F. Skoll [mailto:dfs at roaringpenguin.com]
> Do you whitelist replies from out-of-office software?
> 
> > It is reasonable to assume that if one of my users sends 
> someone mail, then
> > they want a reply.
> 
> Unless the outbound mail is sent by an auto-responder, or by 
> an unsophisticated
> user.

This gives me a crazy idea.  It seems like it would be nice to have an
extension to the SMTP protocol to give out-of-office notification at RCPT TO
time.  That would eliminate the need for out-of-office-replies altogether.

Something like
sending-mta.example.com sending email to receiving-mta.example.org
<<< Banner ESMTP receiving-mta.example.org
>>> HELO sending-mta.example.com
<<< 200 OK
>>> MAIL FROM: <sender at example.com>
<<< 200 OK
>>> RCPT TO: <joe at example.org>
<<< 200 OK
>>> RCPT TO: <fred at example.org>
<<< 500 Don't know any fred, sorry
>>> RCPT TO: <ellen at example.org>
<<< 400 ellen's mailbox is full, try again later
and now the proposed extension:
>>> RCPT TO: <mary at example.org>
<<< 2xx: OK, but mary's out-of-office until mm/dd/yy if it's urgent ask
joe at example.org

Compliant sending MTAs could construct their own out-of-office message back
to the sender including the alert message (which would have to be short)

Matthew.van.Eerde at hbinc.com                      805.964.4554 x902
Hispanic Business Inc./HireDiversity.com         Software Engineer
perl -e"map{y/a-z/l-za-k/;print}shift" "Jjhi pcdiwtg Ptga wprztg,"