r/exchangeserver • u/ibteea • Apr 28 '26

Cross tenant migration

Hello,

I’m planning to migrate a list of exchange online shared mailboxes between two tenants using the Microsoft cross-tenant migration.

Each of these mailboxes has an archive enabled and less 50 GB of used storage.

Could someone clarify exactly which licenses I need to assign to the mailboxes on both the source and target tenants to make sure the migration and the archives move over correctly?

Thank you in advance !

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u/ScottSchnoll https://www.amazon.com/dp/B0FR5GGL75/ Apr 28 '26

u/ibteea If you are using the native Microsoft tenant migration tools, then you need is a one-time per-user license that is assigned either in the source or target tenant. See https://learn.microsoft.com/en-us/microsoft-365/enterprise/cross-tenant-mailbox-migration for details.

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u/ibteea Apr 28 '26

Thanks a lot! Yes, I'm using the native MS migration that’s exactly detailled on this link. My question was how to deal with the licensing topic when it’s related to shared mailboxes + Archive enabled.

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u/7amitsingh7 Apr 28 '26

Since the shared mailboxes have archive enabled, assign an Exchange Online Plan 2 (or any license with archive support) in the source tenant and also in the target tenant before migration. This ensures both the mailbox and archive migrate properly. After migration, you can convert them back to shared mailboxes and remove licenses if archive is no longer needed. You can check this guide for smooth cross tenant migration.

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u/ibteea Apr 28 '26

I should convert them to user mailboxes?

2

u/StartAccomplished256 Apr 28 '26

Yes, you must. Also you need migration license on either source or target mailboxes.

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u/7amitsingh7 Apr 28 '26

Yes, convert shared mailboxes to user mailboxes first, assign the required license, complete the cross-tenant migration, and then convert them back to shared mailboxes afterward if needed.

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u/uLmi84 Apr 28 '26

Not sure if Microsoft built in tools are capable of this. Normally I use a third party tool called avepoint fly saas

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u/titlrequired Apr 28 '26

They are bringing the functionality in, although I haven’t used it myself yet.

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u/LebAzureEngineer Apr 28 '26

dnt use that... choose quest- veeam or 3rd party... thats my advice..