5. Click the Server Settings button. The SMTP Server Options dialog box appears
6. In the Outgoing Mail Server field, type : mail.domain_name
7. In the Server port: 25/587.
8. To the right of Authentication:, choose Password from the drop-down list.
9. In the User Name: field, type your full Username which is your email address(e.g.username@domain.com).
10. Please type your password on the Password field.
11. Click the OK button.
12. You will return to the Accounts dialog box. Close it.
13. Shut down and restart Mail