How to Use a Microsoft 365 Retention Policy to Manage Inactive Mailbox Content

Most Microsoft 365 tenants will have to manage the mailboxes of ex-employees. Retention policies are an excellent method to achieve this goal, if you remember to add mailboxes to a suitable retention policy before deleting their Azure AD account. In this article, we consider Microsoft’s recommendation to use a specific retention policy for inactive mailboxes and how to go about using such a policy.

Inactive Mailboxes Turn Up in Microsoft 365 Compliance Center

Inactive mailboxes have been available in Exchange Online since 2015. A new inactive mailboxes listing is available in the Microsoft 365 compliance center. The GUI isn’t very functional, but perhaps it’s a starting point for some enhanced management capabilities for inactive mailboxes. We’ve only been waiting six years…

Excluding Inactive Mailboxes from Org-Wide Retention Holds

Exchange Online supports inactive mailboxes as a way to keep mailbox data online after Office 365 accounts are removed. Inactive mailboxes are available as long as a hold exists on them. You can update mailbox properties to exclude all or some org-wide holds. If you exclude holds from a mailbox, you run the risk that Exchange will permanently remove the mailbox. If that’s what you want, all is well, but if it’s not, then you might not be so happy.