Bellow are the instructions for setting up email on the iPhone:
Go to the settings menu on your phone and click on the Mail, Contacts, Calendars section.
Click on Add Account
Select Add Mail Account
Fill out the information in this screen.
Select the type of email account you would like. We suggest IMAP for checking email on the iPhone.
Enter the incoming server information. The mail server is mail.YOURDOMAIN where YOURDOMAIN is the domain on your account with us. Make sure to enter the full email address for the username.
Enter the outgoing mail server. It has the same settings as the incoming mail server.
Make sure to go back into the settings of the account and turn off SSL. Select custom port 26 for the outgoing mail server port. Select authentication as password.
Your email account should now be setup. Please contact support if you are having any issues.