For this discussion, let's say my domain is mydomain.com.
I have setup a hybrid mode environment between my on-premise Exchange 2010 server and our Office 365 cloud environment. I performed a remote move to move a single mailbox to the cloud for testing. The move was successful except that, while this account can send email out, no email can be received by it. We received a bounced back message from another SMTP server saying that email could not be relayed.
Checking into the Exchange Message tracking on my on-premise, I see that the messages destined for that user are successfully received but then fail to send out because they are attempting to be sent to the host "www.mydomain.com" (see attached image). Obviously, they should be being sent to Office 365's SMTP servers for our domain. I also noticed that Exchange seems to be using the wrong send connector when attempting to send out to Office 365. Instead of using the "Outbound to office 365" connector, it's using my "Default" one. Can someone please help? I am also working with Microsoft on this, but I don't get the impression that the people I am working with really understand what's going on and I end up trying a lot of unrelated things to try and fix it.
Any help would be greatly appreciated. Thank you.