Microsoft Clarifies Search Capability for Disconnected Exchange Online Mailboxes
After some spirited discussions between the Exchange engineering group and several MVPs (with special credit to the Office 365 for IT Pros technical editor, Vasil Michev), Microsoft has agreed that the content in disconnected mailboxes is not available and cannot be found in Office 365 content searches executed through the Security and Compliance Center. This is now documented online.
A disconnected mailbox is one that belonged to an Azure Active Directory account (cloud only or synchronized from on-premises) where the Exchange Online license is removed from the account. This can be the Exchange Online license within an Office 365 plan (like E3 or E5) or the entire plan. When a license is removed, the mailbox enters a 30-day disconnected state (this doesn’t happen immediately as it depends on a background process). Eventually, the 30-day period elapses and Exchange Online removes the mailbox from its database.
The problem raised by the MVPs arose from some inconsistency in Microsoft’s documentation which led people to believe that the content in disconnected mailboxes could be searched during the 30-day retention period. Tests proved that this seemed to be the case, but it’s always best to go to the source and seek confirmation from engineers who write the code.
Use Inactive Mailboxes to Keep Mailbox Content Online
Inactive mailboxes are the only supported method of keeping mailbox content online and available for searching when a user is no longer licensed for Exchange Online. To make a mailbox inactive, you put a hold on the mailbox before removing the user account from Office 365. The inactive mailbox will remain online as long as a hold is in place. Once the hold (or holds) are removed, the mailbox loses its inactive status and will be deleted.
For lots more tips about how to manage Exchange Online mailboxes, read what we’ve got to say in the Office 365 for IT Pros eBook. And if you find something that we don’t cover well, let us know and we’ll get to it.