Unused mailboxes waste valuable storage space and Client Access Licenses (CAL) as well as potentially creating security and performance issues in the Exchange server. For these reasons it is good practice to find, disable and remove them after preserving the useful information. Exchange administrators can use the ‘last logon time’ to identify mailboxes that are no longer being used. In Exchange 2013, both the Exchange admin center (EAC) and the Exchange Management Shell can be used to find the last logon time of mailboxes.
5 Steps total
Step 1: Finding the last logon time of a mailbox
Enter the cmdlets in the following syntax in the Exchange Management Shell:
Get-MailboxStatistics -Identity <mailbox name>
Step 2: Finding the last logon time of mailboxes in a database
Enter the cmdlets in the following syntax:
Get-MailboxStatistics -Database | Sort LastLogonTime -Descending
Note: The last logon time is not available for users who have never logged on to their mailboxes.
Step 3: Finding the last logon time of mailboxes on the Exchange server
Use the following syntax:
Get-MailboxStatistics -Server | Sort LastLogonTime -Descending
Step 4: Finding the last logon time using EAC
Double-click the mailbox (in EAC, mailboxes are listed under mailboxes of the recipients tab) and then go to mailbox usage tab in the new window.
Step 5: Warning Message :
Mailboxes that have never been used will display the above warning message:
The ‘last logon time’ function can be used to identify unused mailboxes in the Exchange Server – provided the user has logged on to the mailboxes at least once. Having a continuous and pro-active approach to locating and removing these unused mailboxes will help to clean up the Exchange Server; reducing the likeliness of performance issues and increasing overall security.