For outlook express follow these steps :
[1] Open Outlook Express
[2] Click on [Tools -> Accounts]
[3] Click on [Add Mail]
[4] Enter Display Name
[5] Enter your email address
[6] Select your mail server type [pop3]
[7] Enter incoming/outgoing servers [mail.yourdomainname.ext]
[8] Enter Username / Password
[9] Press Next
[10] Press Finished
[11] Goto Tools -> Accounts
[12] Click on Mail tab
[13] Double click on your account name
[14] check this option [My server requires authentication]
[15] Press OK
[16] Press Close
