If you are unable to send mail and are using an Outlook program and Norton Antivirus software, please try the following fix.

When you have selected the "Servers" tab, and placed a check mark in the box next to "My server requires authentication," click the "Settings" button. Click the radio button next to "log on using" then enter your full e-mail address and your passwords in the fields below. Next, place a check mark in the box next to "Remember password" and click the "OK" button.