IPhone email problem

I still have a 3G phone, well for another month or so. I did an update a few days ago and since then it will not receive mail from my .mac account, I get an error message saying "no password provided" and yet when I log into account settings and provide it, it is not saved. It's annoying, but not the end of the world but I would like to solve it until I get a new phone. Any suggestions please?