So resetting and synching the mail settings through iTunes does fix the problem but then it stops working again about a day later and I have to reset again.
Wirelessly posted (iPhone 3G (white): Mozilla/5.0 (iPhone; U; CPU iPhone OS 3_0 like Mac OS X; en-us) AppleWebKit/528.18 (KHTML, like Gecko) Version/3.1.1 Mobile/7A300g Safari/525.20)
Did you update or restore when you installed beta 4?