Strange Relay error HELP! messages being rejected

[MiamiJack]

I have 2 servers which I service through the PMG, when one user (server1) tries to mail the 2nd user (server2) through the gateway, it comes back with the below, both send from their external IP, yet its telling me internal server information and rejecting the message wanting authentication which makes no sense.

SMTP error from remote mail server after RCPT TO: ( receiving user)
550-Please turn on SMTP Authentication in your mail client.
550-ip-172-31-1-196.ca-central-1.compute.internal
550-(sending server) [172.31.1.196]:51794 is not permitted to
550 relay through this server without authentication.

Unfortunately now users can't email each other from different servers via the gateway

Any ideas?

Yes, PMG is fully updated.

Thanks

 

[Stoiko Ivanov]

This is most likely a configuration issue on your downstream server

Please post the complete logs of such a mail from:

* PMG (both the mail coming in from the first server, as well as the attempt to send it to the second server)
* the sending system
* the receiving system

else it's not really clear where the issue is rooted

 

[MiamiJack]

Thanks for the response, I will try to gather the info from a newer event, unfortunately some of these are Exchange so logs aren't always easy to get.