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
Hopefully this setup works.
If it does not, kindly use your ISP's SMTP or contact your Network Administrator