Display only outgoing emails in Activities subgrid

Hi All

I have got this requirement of changing activities view to not display received emails, i.e., Subject beginning with Re:/Fw:/FW:/RE: I have updated the view to not show these but still I'm seeing lots of replies and Forwarded activities. I have tried both contains and beginning but it doesn't work. 

We actually can't disable tracking as we are using it for some other important task. Only way is to change the view filter please suggest. Thank you