Step 2
On the E-mail Accounts Popup , choose to View or change existing e-mail accounts

Step 3
Under the list of E-mail Accounts, click on the account that is sending and/or receiving email from your domain name.

Then click on Change...

Step 4
Make Sure the Internet E-mail Settings are correct, check POP3 and SMTP servers, and make sure your User Name is your full email address.

Then click on More Settings...

Step 5
On the More Settings Popup, click on the Outgoing Server tab. Then make sure the My outgoing server (SMTP) requires authentication
checkbox is checked.

Also, click on Use the same settings as your incoming mail server as well.

Click OK.