Only works with newer iPhones:

1. Press the Home button and select Settings > Mail, Contacts, Calendars.
2. Under Accounts, select Add Account…
3. Select Other.
4. Enter your name (which will show in the from field) and your full email address.
5. Enter your email password and description (we recommend the full email address as your description).
6. Press Save.
7. Select IMAP or POP
8. Under Incoming Mail Server, enter mail.domainname.com
9. Enter the  full email address as your User Name.
10. Enter your email password and then scroll down.
11. Enter the same information under Outgoing Mail Server.
12. Press Save.