I have a client who has a funny sort of setup.
Its a doctors surgery who got brought out by a pharmacy. The doctors surgery was independent running its own sbs server and receiving mail etc as per a normal site.
When the pharmacy brought them out, the old IT guys moved the domain/sbs server from their old site and dumped it as per normal into the new site.
The pharmacy and the doctors surgery share the same internet connection through Telstra managed wan. This is all working so far.
The old IT guy got telstra to create a new external IP that is "assumingly" NAT'd through to the sbs server on port 25 to accept the mail on. This seems to be working correctly.
The pharmacy has its own domain name however and has telstra hosted mail. This is then POP'd to the sbs server and is supposed to be delivered to the users associating mailboxes. This doesnt work. When I took over, they were unable to receive the mail as the POP mail was from a different email domain to the users mailbox. To work around this, I created a new SMTP connector with the new domain name and turned the server off being the authoritive body so they wouldnt get bounce backs etc when the sbs server couldnt find people outside of the AD. This seemed to work for about 2 weeks fine. I went back to site today to find the POP connector was not receiving / Connecting / event logging etc. Restarted all the services etc and didnt come up, So I rebooted server. Worked fine, POP connector was working again.
I decided to send some test emails and started getting this bounceback message:
<email@example.com>: internal software error. Command output: Message is looping. Existing Delivered-To for
I cannot understand what has changed from doing a reboot that would cause this issue especially when it was working successfully after the configurations I made.
I hope I have given enough information, unfortunately I wont be able to post any screenshots etc at this point of my SMTP connectors, POP Connectors, Default Virtual SMTP as I dont have remote access to this site. I will be back there on Monday however, trying to do any recommendations you guys might come up with.