This isn't the complete answer to your problem, but one of the puzzle pieces
that might help your situation.
smtpd_recipient_restrictions = reject_non_fqdn_sender
http://www.postfix.org/postconf.5.html#reject_non_fqdn_sender
We have received a big batch of phishing emails that was not properly detected
(hence not blocked). They all shared a special characteristic:
To: Recipients
From: Administrateur
Reply-To: <nore...@admin.fr>
Return-Path: <>
To and From are not qualified email addresses, Reply-To is bogus but qualified
even though admin.fr does not have an MX record. Envelope Mail From /
Return-Path is blank.
Is there a proper way to block this kind of junk in Postfix or do I have to
rely on my antispam (that will need tuning, obviously)?
