Email based trouble ticketing system

[Travis Roy]

Does anybody know of a good email based trouble ticketing system.

We currently use Request Tracker, but it has some limitation. One is 
that when you reply to a customer if you don't do it within the 
ticketing system it usually generates another ticket.. And when our CTO 
does most of his stuff via his blackberry now, that's a lot of tickets.

It doesn't need a web interface at all, but one would be nice for reporting.