Personally I hate the program
I think its the one mainstream application that gives me the most heartache when dealing with customers. Where possible I wean them off it and onto Windows Live Mail (yes I know that had issues but at least its customer - proof)
If you don't want to go down the M$ route and want a decent e-mail program take a look at The Bat!
You have to pay for it, but it works
RITLabs. The Bat! Email Client