The first thing you need to do on an iPhone is delete your existing email account setup on the iPhone to clear the deck and start again.
Then create a new POP3 email account with the following example settings. Replace all references to "expiry.com" with your own domain name and replace the "gerry" portion with your own user name.
POP Account Information.
Name: your name
Address [email protected]
Description [email protected]
Incoming mail Server
Host Name: mail.expiry.com
User Name: [email protected]
Password: your password
Outgoing Mail server
SMTP: mail.expiry.com
Other SMTP servers: Off
Then Click on the Primary Server link to open up the next page
Host Name: mail.expiry.com
Username: [email protected]
Password: your email password
Use SSL: OFF
Authentication: Password
Server Port: 587
That's it - email should start flowing through immediately after you save these settings.