1&1 Email on iPhone.. HELP!

I've been trying to setup my 1&1 IMAP email account on my iPhone but haven't had any success getting it to map out the folders properly.. i've tried many configs: changing ports around, using SSL/not SSL, mapping out 'IMAP path' to 'INBOX'.. still can't get anything to work properly. The IMAP acct works fine on my entourage on 2 different computers and also Outlook on my PC.. Any insight on this? I need to get this thing running right.. it's making me crazy! Btw.. my gmail and other IMAP accounts work fine on my iphone, this is the only issue!

Surely this is something you should take up with 1&1?