Forum Discussion
Cross Tenant Mailbox Migration: Step by Step Guide
Hi awaaziz,
First of all, let me shared with you the new stpes for a cross tenant mailbox migration, as this article isn't up to date, sorry: https://learn.microsoft.com/en-us/microsoft-365/enterprise/cross-tenant-mailbox-migration?view=o365-worldwide
Second, If I understood correctly your scenario, ( target users already have a mailbox in EXO ), this process will not support it. ( Existing mailboxes have their own ExchangeGuid, ArchiveGuid... And you need to set those attributes previously on new created mailusers ). Delete the mailboxes and strat from scratch will also not be a solution, ( unless we're talking about a few mailboxes with no much content... Then that could be backed up ).
Possible solutions could be create new mail users on target side, migrate from the source to them, and after that move the mailbox content to the original mailboxes, ( a nightmare and only feasible if we're talking about a few mailboxes again ).
Also PST export/import... But again, for a few mailboxes and taking in mind the security risks following that procedure.
Maybe if you could provide me more info, ( number of users, mailboxes sizes, etc... ), I might have some other idea.
The new mail users will be created in the cloud and for me the user must use the synced account
- In that case, you should be able to go ahead with a new mailuser, set it accordingly, migrate the mailbox and, after that, match the new mailbox with the correct user due the ImmutableId.
- So i must :
Create a mail user as a cloud object in the target tenant.
Migrate the mail box from source to target.
Match the synced account with the mail user in the target tenant using the Soft or hard matching method- Yes, from my perspective that's the only way, ( I did it in the past and softmatching didn't work... We needed to hardmatch with ImmutableId ).
1- New Mail User
2- Set Mail User, ( attributes described in the article, from the source tenant ).
3- License the Mail Users. ( ensure that attributes are correct before this step ).
4- Migrate the mailboxes, ( once completed, the mail users will be converted automatically to mailboxes ).
5- Match the O365 users/mailboxes with the local synced account.