Hi all,
Long story short, our client has Exchange on prem and is using O365 for archiving only. When trying to get a user's account to attach to the archive while working with O365 support, they ended up changing the mailbox's ExchangeGuid to the same as the ArchiveGuid. Now when the end user opens Outlook, she's dropped directly into her archive instead of her on-prem mailbox. As you might imagine, that's causing all sorts of trouble.
I've seen references to using Set-RemoteMailbox, but this doesn't work since it's not a remote mailbox for O365, it's on-prem only. I verified this with other mailboxes in our own environment as well. And Set-Mailbox doesn't have a switch for -ExchangeGuid.
Any thoughts on what else should be done to get this back to normal, so her ExchangeGuid matches the on-prem mailbox again?