How to Find Last Logon Time for Exchange Mailbox Users
The last logon time of an Exchange 2010/2013/2016 mailbox user can easily be found by running the Get-MailboxStatistics cmdlet in the Exchange Management Shell.
You can further sort the info by including and running the following command:
Get-MailboxStatistics -Server EXCH | Sort LastLogonTime -Descending
And export it to a CSV by adding an Export-CSV option like below:
Get-MailboxStatistics -Server EXCH | Sort LastLogonTime -Descending | Export-CSV c:\lastlogon.csv