Today, we want to talk about a request we have from clients about how to retire Office 365 mailboxes. You may find yourself with an employee who has left the company, and now you face the question of what to do with the mailbox data that employee has left behind. For some companies who do not face compliancy regulation, the matter is as simple as removing the users licenses and you can be on your way. Some administrators may have the foresight to back-up the mailbox to a PST, but this is still not a very robust way of holding onto the mailbox data.

For other companies that do face regulatory compliance and have their mailboxes on litigation hold, this option is not acceptable. The administrator can choose to retain the mailbox and simply disable the user account, but this consumes a user account. It appears that there is no choice but to maintain the license and litigation hold in order to keep the mailbox on litigation hold/EDiscovery and keep with compliance.

However, we have another option within Office 365 called Inactive Mailboxes. An administrator has an option to place a mailbox on an indefinite In-Place Hold, to ensure we retain emails from deletion for Discovery purposes, and also to free-up the users license so that it is not being actively consumed for a user that no longer works with the company.

The process for this the Inactive Mailbox is relatively straight forward. You need a license type which supports Discovery/Litigation hold, which is Exchange Online Plan 2, an E3, or an E4.

The Process

  • From the Exchange Administrator Center, ensure that you are a member of the Discovery Management RBAC Role Group. This is located in the Office 365 Exchange Admin Center – Permission – Admins Roles – Discovery Management. Add yourself as a member.
  • In the EAC, go to the Compliance management tab, and then the In-Place eDisocvery & Hold tab. You will create a New (+) Mailbox Search.
  • Give it a name and a description, e.g. Indefinite hold of John Smith, 2/26/2014.
  • Click Next, and on the next page, specify the user as the only user to search and hit next.
  • You will include all user mailbox content, so hit next on this page.
  • Check the box for “Place content matching search query in selected mailboxes on hold.” You can either give it a date or hold it indefinitely.
  • Click finish. This saves and creates the mailbox Search.

Once the search has been created, monitor the search status. It should go from a queued state to eventually a Search Estimate Succeeded state. You can now delete the user or remove their license, and their mailbox data will be maintained. Note that the mailbox may continue to show up under the Recipients/Mailboxes tab for 30 days while the litigation hold grace period on the mailbox expires. This has no bearing on the In-Place hold you have just created.

You now have a few options for exporting the data

If you click on the magnifying glass, located under the options on the In-Place eDiscovery hold page, there are 3 options. You can Estimate the search results, which will show you an estimate on the right hand side of found data. Estimate search results is best used for query-based searches. The other two options you’ll end up using more. You can select to copy the search results, which will copy the emails to a target mailbox. This makes it easy for giving your legal department a copy of an email they have made a Discovery request for. Alternatively, you can click on “preview” results to open a new webpage showing you what is found from the search.

The last option is the PST Download option, this is represented by the arrow pointing down to a horizontal bar. You can download the entire mailbox to a PST file if you so choose, as many times as you want.

So, now that your mailbox has been retired and is now inactive, this frees up your licenses, without having to worry about making sure you retain compliance for Discovery purposes on the mailbox.

Follow up reading

You can review the licensing matrixes here:

Inactive Mailboxes:

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