My wife has a Samsung Galaxy s, but she keep complaining that her phone doesnt receive emails, she refreshed and waited but can nvr get new emails coming in although there is new emails in her mail box when she check through browser...

My wife's samsung galaxy s is having unacceptable slow connection to internet, but my desire is fine, we both using Digi. Her signal is full when having problem with internet, her iphone 3gs has no problem at all. So we suspect it is the galaxy s problem. could it be the radio problem? what can we do to fix it?