This tutorial will teach you how to setup an IMAP email account on your iPhone. The first thing you need to do is make sure that the email address exists in your hosting account. If it doesn't, go ahead and create it in your control panel first.
Now, on your iPhone, locate and press the settings icon. This will open a Settings screen, where you will select "Mail, Contacts, Calendars". Under Accounts, select Add Account. Now choose Other. On the new screen, select the Add Mail Account bar.
The New Account window will open, and you will need to enter the Name, Email address, and Email Password of the new email account that is being added. The Description line will fill in automatically, but you can change that description if you would like. When you are done, press the Next button in the upper right corner.
In the next screen, make sure the IMAP option is selected. Next you will need to enter your Incoming Mail Server settings. Enter the Host name, (which is usually mail.yourdomain.yourdomaintdl), the User Name, and the User's Password. Now you need to fill in the information for the Outgoing Mail Server. When you are finished, press the Next button in the upper right corner. Now press Save.
That account should now be set up and be added to the Accounts list. To check your mail, press the Mail icon, and then select the email account that has just been set up. Any email in the account should then be displayed, and you can click on the header to read it.
That concludes this tutorial. You now know how to Set Up an IMAP Email Account on your iPhone.