Noel Jones wrote: > 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
I like the idea of verifying addresses, but this stuck out. <snip from the "Postfix Address Verification Howto"> WARNING The sender/recipient address verification feature described in this document is suitable only for low-traffic sites. It performs poorly under high load; excessive sender address verification activity may even cause your site to be blacklisted by some providers. See the "Limitations" section below for details. </snip> ------------------ what does the author consider as being low traffic?
