This may vary depending on how your Outlook was setup.

1. Click Tools, the Accounts or Services

 

2. Click the mail tab and select the properties for your account

 

3. Replace the POP3 and SMTP servers with mail.yourdomain.com

4. Replace the Userid or account name with the complete email address

5. Be sure to select "This server requires authentication".

 

6. Click OK, Outlook may require a restart

7. Click Send/Receive to verify your settings