verify receivers clarification

[MiamiJack]

Hello All,

I wanted to confirm how the Verify Receivers function works for the returned message as well as not rejecting as expected.

I have Verify Receivers set to 550 ( reject ), if I intentionally send a wrong email address to an exchange server protected by PMG, the rejection message actually comes from the actual exchange server and not PMG, is this correct/expected?

On another domain I have a domain where if a wrong email address is sent to, it puts it in quarantine (probably because it is spam) and doesn't rejected.
As an example EatFood@abc.com doesn't exist as a real mailbox, the message for it gets delivered to quarantine, shouldn't this message be rejected from the beginning and never make it to quarantine? ( this one goes to a control panel box, and I did set permissions for PMG to query that server to allow the verification )

Thank you!

 

[Stoiko Ivanov]

the verify receivers option enables reject_unknown_recipient_domain , reject_unverified_recipient - see http://www.postfix.org/ADDRESS_VERIFICATION_README.html - nothing more, nothing less

That being said - Exchange is known to not handle this well in the default setting (it answers with 250 even for non-existent addresses) - this is most likely the cause of the issue you're describing: https://serverfault.com/questions/493261/exchange-2013-recipient-filtering-reject-after-rcpt-to

I hope this explains it!

 

[MiamiJack]

Thank you @Stoiko Ivanov .

Does PMG create the 2 files reject_unknown_recipient_domain , reject_unverified_recipient because I'm not seeing them in /etc/postfix?

The Exchange part makes sense, and we did verify it was on, but Microsoft dances to their own beat, I believe we are also seeing this with O365.

In respect to the cpanel server however, we do have it on and verified it, but we are still getting unknown email addresses getting spam quarantined, rather than be rejected.

Thanks!

 

[Stoiko Ivanov]

Does PMG create the 2 files reject_unknown_recipient_domain , reject_unverified_recipient because I'm not seeing them in /etc/postfix?

these are 2 settings in postfix' main.cf? - see http://www.postfix.org/postconf.5.html#reject_unknown_recipient_domain and the howto...

In respect to the cpanel server however, we do have it on and verified it, but we are still getting unknown email addresses getting spam quarantined, rather than be rejected.

please post the logs of such a message ... else it's not really possible to help...
the CPANEL server needs to reply with a 5xx code after the RCPT TO command for recipient verification to work