Got a strange issue. We have a hybrid setup with Exchange 2010 and Office 365. I have recently migrated 50 users to Exchange Online with our office 365 subscription from our Exchange 2010 server. On the whole emails that are sent and received from the Exchange Online accounts are working fine without any issues.
However, emails to certain users whose mailboxes reside on the exchange 2010 server are not being received from Exchange Online users. I have checked the message trace on office 365 which shows as being delivered, however when I check the message tracking on the Exchange 2010 server for the receiver of the email, it doesn't even show anything that the email has actually reached the server.
I thought about migrating the affected users to exchange online to see if that made any difference as they will be migrated to there eventually. However, during identifying the affected users, I noticed one thing in common. When I try to migrate them via the migration wizard in exchange online, they don't show up as being able to be migrated. They appear if I select the option to move them from Exchange Online. However, their mailboxes are fully functional on the exchange 2010 hybrid server and can be fully edited.
Also, when I try to migrate the mailbox from exchange online I receive the error message MigrationPermanentException: Cannot find a recipient that has mailbox GUID '62b138cd-c49b-4a4e-89a4-bad5dad1c152'
Can anybody point me in the right direction to get this resolved.