RT moved to Azure mail to our office 365 no longer working

Good Day, We recently migrated our RT server (CentOS7) running Postfix to Azure from the data center environment where it was before. Incoming mail is working fine and tickets are being opened. Outgoing mail is working to external (non Office 365 domains) like gmail and yahoo. We have added the new public IP of the RT server as an allowed connector in Office 365.

We did not set up this server originally, but wondering if there is something in the server (firewall rule) that would affect its ability to send mail out now that it has both a new private and public facing IP?

Or if Azure is blocking it from sending to Office 365. We do have a windows smtp server that is sending from azure to office 365 just fine.

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Are you getting any delivery failure reports returned from Office365? If the RT machine is sending out email directly (rather than going through another mail gateway), then the fact that its sending OK to machines outside of Azure tends to imply that its firewall rules are allowing SMTP traffic both in and out OK, so I’d be looking at what the MTA logs on the transaction talking to Office365 and/or what Office365 returns and/or logs itself.

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Maybe I should try to edit the postfix.cf file so that it relays mail to our windows smtp server that is NOT having an issue sending from azure to office365 and beyond.

Thank you for the additional information. Looking via tail -n 100 maillog I see entries like this
Sep 16 09:25:06 rt4 postfix/smtp[5094]: A8F886054719: Server]:54798 is currently not permitted to 550-relay through this server. Perhaps you have not logged into the pop/imap 550-server in the last 30 minutes or do not have SMTP Authentication turned on 550 in your email client. (in reply to RCPT TO command))

I edited /etc/postfix/main.cf for value relayhost to use our internal windows smtp server and it’s now working. Just going to keep it this way

For future reference, this looks like the Office 365 MTA was expecting your MTA (postfix) on the RT server to authenticate its transaction using SMTP-AUTH. But if you’re going through a windows SMTP relay and it works now, great! :slight_smile:

Ah okay. Interesting that this would change once the server resided in Azure vs on Prem. Office 365 much have a different rule for that depending on where the traffic is coming from. Both public ip from where the smtp traffic was originating were added as connectors in Office 365.
Thank you again, GreenJim