Why email address dosn't work?

[Sudhakar]

    *  Make sure your user name and password is all lowercase.
    * Make sure you have created the email address in your control panel.
    * Change the user name to the full email address. Example: username@domainname.com

Still not working?

    * Change your incoming and outgoing mail servers from mail.yourdomain.com to the ip address listed in your welcome email.
    * Make sure you have "My server requires authentication" enabled otherwise it will not work.