MessageTrackingLog not showing correct results

I am trying to find out when a set of users has last sent and received an email. In my search for the right command, I can see that I not always get the right result. 

As an example:

Get-TransportService | Get-MessageTrackingLog -Recipients me@domain.com -EventId deliver | sort TimeStamp -Descending | select -First 1|fl

This returns:

Timestamp               : 09-05-2016 16:25:29

However, if I specify the -Sender I get the correct result:

Timestamp               : 08-06-2016 15:00:02

Is there any other way to get this task done from the Shell?