I cannot send or recieve E-mails thru windows mail.

When i try to send an E-mail thru windows mail it says it tries and then an
error message appears. I know this seams like a common question but I would
apreciate the help. I can send E-mails thru aol. Just fine. But when i try to
reply to a craigs list add, it uses windows mail. So it never works the error
message is as follows
The message could not be sent. The authentication setting might not be
correct for your outgoing e-mail [SMTP] server. For help solving this
problem, go to Help, search for "Troubleshoot Windows Mail", and read the
"I'm having problems sending e-mail" section. If you need help determining
the proper server settings, please contact your e-mail service provider.

The rejected e-mail address was ''. Subject
'tailor/sewing/alterations', Account: 'imap.aol.com', Server: 'smtp.aol.com',
Protocol: SMTP, Server Response: '556 CLIENT AUTHENTICATION REQUIRED. USE
ESMTP EHLO AND AUTH.', Port: 25, Secure(SSL): No, Server Error: 556, Error
Number: 0x800CCC78


Thank you very much for any help you can give.