Just went through a massively frustrating call with Microsoft, thought I'd reach out here. We have an exchange standard on premise install with about 14 mailboxes that's been humming along for 3 years. Only 2 of them recently had an error pop up a month ago with a "your mailbox has been temporarily moved on Microsoft exchange..." with the option to use a temporary mailbox or use old data. In all cases, the alias changed to that outlook_91f898214y98ye198yt98198yc@outlook.com (random numbers and letters used for example) as well as the data file and the outgoing server. I've seen some cases of this happening during a 365 migration but that's not the case here at all. All Office licenses are purchased outright Office 2016 Home and Business.
It seems like it's treating these accounts as outlook.com accounts after accepting exchange credentials.
We've tried the following:
Profile delete, rebuild.
Same as above, manually deleting data file then rebuild
Same as all above then unchecking cached exchange mode
Create new Windows user and repeat steps
Fully uninstalled Office and reinstalled
Uninstalled all windows updates from October and September
None of this worked. OWA works, Windows 10 "mail" client works without issue. Mobile has no problem. This is strictly an Outlook issue it seems and it's only with our 2 most recent Outlook installs, all other users have no problems.
Hoping for some ideas, Microsoft seems clueless about this and wants to extract $500 from me to fix an issue I almost certain didn't cause.
