Try this in the search box:

EMC and EmailXtender and 0 IN xvMsgClass

I think the '0 IN MsgClass' bit limits the search to email messages only.
Let me know if that helps.

Yes, 0 in xvMsgClass should do the job.

Following are few more I could think of

Contacts=1
Appointments=2
Tasks=3
Posted notes=4
Journal entries=5
Sticky notes=6