Hello,
Some time ago we experienced a failure with our sole on-premise mail server (HQ-Mail), giving us reason to migrate to a new one (HQ-Mail2) so we can decommission or repair the old one. Presently, all mailboxes exist on HQ-Mail2, and we have tried to
copy as much as the old configuration as possible; all the virtual directories are the same, every Receive Connector has been replicated there, and HQ-Mail2 has been added to the original Send Connector. Additionally, all network/dns routing has been configured
so our customers are connecting to the new mail server instead of the old one, and all external emails are being passed directly to it from our mail-forwarder (no-ip). We have even assigned fresh certificates to it.
Mail is flowing and being delivered without issue, but for some reason we're seeing all mail being sent first to HQ-Mail2 as expected, but then being passed on to HQ-Mail. After which, it then either goes out to the Internet, or is delivered from HQ-Mail directly to the intended mailbox (being passed back to HQ-Mail2).
If we attempt to remove HQ-Mail from the send connector, outbound mail stops flowing (Sits in the Unreachable queue) until we add it back, so we're hesitant to shut it down for repairs and we're not sure where else to look for troubleshooting. Any advice would be appreciated.
Thanks for your time,
Canezar
Edited Additional Information:
We are using the default send connector; where it used to only be HQ-Mail in the connector, we have added HQ-Mail2 as well - there are no smarthosts or network appliances for external emails. The DNS settings for both machines are the same and I am able to resolve both internal and external hosts on HQ-Mail2. I also took the liberty this evening to test the mailflow with HQ-Mail offline, and nothing is delivered as we had suspected - whether it is outbound or inbound.