Terry L. Inzauro wrote:
List,
I operate a backup mx for one of my customers. In doing so, I have run into an
issue where I must accept all email regardless
of weather or not the messages is destined for a valid email account in my
customers email system (which is MS Exchange 2003).
I thought about asking my customer is they would export a list of email
addresses for which they want backup MX service for
so I can place that in a relay_recipient_map, but that process requires ongoing
admin time and might not appeal to them.
If their system rejects unknown recipients during SMTP, you
can use the reject_unverified_recipient feature to let postfix
manage the valid recipient list for you.
Do this inside a check_recipient_access map to limit the
address probes to only this domain.
http://www.postfix.org/ADDRESS_VERIFICATION_README.html#recipient
The majority of the junk mail I am seeing is in the form of From: u...@domain
and RCPT: u...@domain which is obviously
forged. Would a header_check be the way to go here in order to match and
discard the junk mail in this case? If so, what
would the pcre check look like?
header_checks examines one header at a time, so you can't
compare From: <> To:.
You can use a policy server such as postfwd to compare
envelope sender vs. recipient, or a content_filter such as
spamassassin to compare the headers.
I understand that legitimate users wouldn't be able to send themselves email,
but that fine with me.
-- Noel Jones
