Exchange Migration

[Jawloms]

I've just moved all of my users from onsite up to M365. We had a hybrid configuration. I have one mailbox which wouldn't migrate so I figured I'd just export all the stuff to a PST from the Exchange server, and import it in to their new mailbox. I cannot for the life of me figure out how to create the user a mailbox in M365 (new users I'm obviously fine with!). They have an account up there which is sync'd from AD, they have an Exchange licence, but in their "Mail" properties it just says "This user's on-premises mailbox hasn't been migrated to ‎Exchange Online‎. The ‎Exchange Online‎ mailbox will be available after migration is completed". How do I tell it I don't want to migrate them? I've found a couple of things telling me to delete the Exchange attributes from their AD account, but that sounds a little scary and not official. County have changed all my DNS stuff now so I believe that M365 can no longer "see" my onsite stuff in the way of the hybrid setup, but the AD sync is still sync'ing.

 

Thank you

 

Stuart

[ThomL]

Backup the attributes so you can revert if needed, then wipe them from the user and sync?

[chaplic]

The scary stuff you have seen will likely be accurate. If you

 

a) license the account

b) delete all the MsExch* attributes from the AD account (take a note of them), it will create a new mailbox in the cloud, after a couple of syncs.

 

MsExchangeRemoteRecipientType and a few other attributes define where the mailbox is hence why this should work.

 

BTW M365 can still see your on prem stuff as it's all synced via AD in terms of user config

[howartp]

We just migrated Year 12 last week.

 

Eventually got all but 7 mailboxes migrated via various means including removing those properties you referred to.

 

I had to unlicense them, disable-mailbox, enable-mailbox then restore mailbox content from Veeam backup to (now empty) onprem mailbox, then do sync again.

[Jawloms]

Scary looking attributes deleted, waited a while for sync's to happen, and now she has an O365 mailbox!

 

Thanks all.

[chaplic]

For an extra gold star, review those same attribtues to say if AADC has updated them ;-)

 

BTW just noticed you're in suffolk, howdy neighbour