A reasonably reliable method to find out whether a mailbox is used for mail-activities, is to use the MessageTrackingLog. i used the following comdlets to find out whether a mailaccount was used. The cmdlets work for both Exchange 2013 and Exchange 2016
$emailaddress = "admin@itexperience.net" Get-TransportService | Get-MessageTrackingLog -Recipients $emailaddress -ResultSize unlimited # -Start (Get-Date).AddHours(-168) Get-TransportService | Get-MessageTrackingLog -Sender $emailaddress -ResultSize unlimited # -Start (Get-Date).AddHours(-168)
Note: if the mailbox has multiple emailaddresses,: check all of them!
Also: remove the # to specify a timeframe in hours. You can, for example search the past 720 hours (30 days).
The cmdlet Get-TransportService will enumerate all Exchange CAS-servers. Then, messaging logfiles will be searched on all these servers
