I have two email accounts setup on my iPad. A lunarpages.com account and a MobileMe account. The mobileme account continuous to work fine but the lunar pages account has quit (ie: can't download or send emails).
The lunar pages account works fine on my iPhone, MacBook Pro, and desktop PC, so I don't believe there's anything wrong with account. It just, after a couple of months of working fine on my iPad, quit working. I've tried deleting, and resetting up the account, but still no luck.