When moving mailboxes to Exchange Online. The remote server returned an error: (503) Server Unavailable… mrsproxy.svc is unavailable, service is too busy or no endpoint.
I spent many hours troubleshooting and opening several support tickets with Microsoft, but in the end, I was able to fix the problem on my own. I believe it would be helpful for others to share my documentation of these procedures. The help from Microsoft O365 support was quite disappointing. They seemed to repeatedly ask the […]