Settings > Mail, Contacts, Calenders > Add Account > Other, and fill in the appropriate information and click 'Save'
(The password field is the password for the email box)

On the next Screen:
- Chose POP instead of imap (unless the account was set up as imap).
- Put mail.$domain.com in for your Incoming Server Host Name
- The username is the first part of your email address in all lower case (the part before the @ sign)
- The password is the password for the email box.
- For the Outgoing Mail Server Host name put mail.$domain.com
- Leave the username and password fields blank.
- Click Save

When it asks 'Cannot Connnect Using SSL' click Yes
- You may get asked this question a few times, continue to click Yes.

The default settings on the iphone may be different than what the server uses so you will need to correct those. If your screen does not go back to the Mail, Contacts, Calenders section you will need to go back to it now.

- Click on the email address you have just set up (should be at the top).
- Click on SMTP (under where is says Outgoing Mail Server)
click on mail.$domain.com
- Where it says 'Use SSL' switch that to Off.
- Were it says Server Port (defaults to 587) you will want to click on it and change that to 25
- port 587 may work for you as well, but 25 is the default port on our servers

After you do this you will want to change the incoming mail server setting. On the top of this screen click on SMTP (in the top left hand corner) to go back to the previous screen.
- click on the button in the same location that comes up on the next screen (should list your email address) to go back to the previous screen.
- Click on Advanced
- Were it says 'Use SSL' switch that to Off
- Were it says Server Port click on it to change it 110

After that you can return to the main screen and select the Mail option at the bottom.