Wait while the phone saves and then it should display a new screen with extra settings. Make sure that the IMAP button is selected at the top left and you should see the Name, Address, Description and Password should have carried over.
Make sure IMAP is selected
Scroll down and enter "imap.1and1.com" without the quotes in the Host Name field and your
full e-mail address in the User Name field under the Incoming Mail Server section.