Palm Treo 755p

I'm a new user of 755p with sprint. I have company email that I set up with a pop account. I can send and receive mail fine. However, everytime i want to get new email I have to press GET. It doesn't come in automatically like other phones I used before that have Windows mobile. Do I have to change a setting or do I have to get a secondary program (if so which is recommended). Any help is greatly appreciated Thanks! - Swan