How to identify unused Exchange mailboxes?

Administrators routinely identify all the unused and inactive mailboxes in their organization. The two main scenarios where you would be asked to discover inactive mailboxes are as follows:

  • Storage issues: You may be asked to discover all the inactive mailboxes for space optimization.
  • Licensing: Licenses do not exactly come cheap. In order to cut costs, your organization may launch an audit to see if any dormant mailboxes are using licenses that could be better used elsewhere.


Exchange Reporter Plus has a whole category of reports called the account status reports, under the Reports tab.

Account status reports

Of particular importance here are the three reports on inactive mailboxes. Depending on your organization's policy, you may deem a mailbox to be inactive if:

The mailbox hasn't been used for a while: Use the Inactive Mailboxes by Last Logon Time report to identify mailboxes that haven't been logged on to for a particular time period.

The User has not sent/received an email in a long time: Use the Inactive Mailboxes by Last Sent Mail and the Inactive Mailboxes by Last Received Mail reports respectively. These reports are particularly helpful if any Antivirus tools are being used for your mailboxes, which changes the last logon time.

In addition to this, Exchange Reporter Plus has several features and reports that help you administer your on-premises and Exchange Online environments efficiently. Discover the different features available that help in reporting, change auditing, and monitoring here.


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