Issue: Customer couldn’t access office 365 mailbox using the unified URL and kept getting “something went wrong, user has nomailboxexception” errors.
Notes: Customer was running hybrid configuration with Office 365 and Exchange 2013. Also the mailbox is a remote mailbox
Resolution: TargetOWAURL for the organization relationship at customer site was
Issue was resolved when customer modified remote routing address of the remote mailbox to firstname.lastname@example.org
The service domain in the target OWA url needs to match the remote routing address of the remote mailbox