SMTP Authorization

[Jeff Graves]

I've been looking for a SMTP server authorization mechanism. Basically, it
would work something like a system connects trying to send mail that's from
user at domain.com - the receiving server queries the DNS records for
domain.com and checks that the connecting IP is authorized to send mail for
the domain.com domain. Plugging this into a MailScanner install could do a
couple of things: block it, force greylist milter, assign a higher
spamassassin score (or whitelist), etc. I've seen a few drafts out there for
such an implementation but no working software. Does anything exist
(preferably that works with MailScanner and sendmail)?

-- 
Jeff Graves, MCSA
Image Source, Inc.
508.966.5200 x31 
www.image-src.com