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Office 365 E3 - best way to keep access to old mailboxes

paulc2000
paulc2000 asked
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Last Modified: 2017-03-10
Hi all,

We have E3 licences for all our users, with archiving enabled (if that matters).

We would like to keep access to our ex-employees' mailboxes in perpetuity, but as cheaply as possible.  Aside from moving old mailboxes to cold storage, what are our options?  I was told by someone knowledgeable in the area that even unassigning an E3 licence will keep the mailbox intact in Exchange Online.  So, I called Microsoft to confirm, and they tell me no, that's not correct.  30 days is the max they guarantee recovery for.  So I sent her a Microsoft URL that states this:

"Caution: When a user’s license is removed, all data that is associated with that user account is held for 30 days. After the 30 day grace period, the data is deleted and can’t be recovered, except for documents that are saved on SharePoint Online and the data in the user's mailbox. The user mailbox will remain in Exchange Online until it is deleted, permanently removed or purged by the Office 365 admin. You can reassign a license to the user and make the mailbox active again."

https://support.office.com/en-ie/article/Assign-or-remove-licenses-for-Office-365-for-business-997596b5-4173-4627-b915-36abac6786dc

So I was left with little confidence that the support staff had any clue about this issue.

Does anyone know for sure?  The paragraph above is very confusing too: "we delete all data except files and mailboxes."  What's left?!

Thanks,

Paul
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Adam BrownCloud Security Consultant
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Commented:
With the O365 E3 license, you have the ability to use the Inactive mailbox feature in Exchange. https://technet.microsoft.com/en-us/library/dn144876(v=exchg.150).aspx has details on what you can do, but basically it allows you to retain mailboxes for users indefinitely (This is allowed by the E3 license because it includes the Exchange Archiving features, which provide long term storage and retention capabilities in Exchange online).

Essentially, by default, all mailboxes (even E3) will be deleted after 30 days. However, mailboxes that are placed on Litigation hold or that are part of an InPlace hold will be retained until the hold is removed or the mailbox falls out of the scope of an existing InPlace hold, even if the license for the user of that mailbox is removed. That can be forever if you want. Note, though, that this feature is only available for Exchange Online subscriptions that include Exchange Archiving (E3 subscriptions to O365 do include this)

Author

Commented:
Great, many thanks for your reply.

So, in essence, to retain mailboxes indefinitely at no cost, we should set them to litigation hold with no expiry, then remove any licences from those users?

Thanks,

Paul
Adam BrownCloud Security Consultant
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Commented:
That's correct.
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Author

Commented:
Thanks both.  Do I *need* to remove the user object also?  Or is removing the licence sufficient?

I found this page which states to remove the user's account:

https://technet.microsoft.com/en-us/library/dn798632(v=exchg.150).aspx

Just wondering if it's a necessity.

Thanks,

Paul
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Commented:
Yes, if you want to keep the user account, use a shared mailbox instead.

Author

Commented:
Sorry for the questions, but why is it necessary to remove the user object?  Why is removing the licence not enough?  Thanks
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This problem has been solved!
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Commented:
Excellent, thank you both very much for your answers.