Error message on Outlook express 6

[angel123]

I get this error message on Outlook express 6. I cant send or recieve messages cause this error message shows up. Please help!!The message could not be sent because the server rejected the sender's e-mail address. The sender's e-mail address was 'mom951@sbcglobal.net'. Subject 'test', Account: 'pop.sbcglobal.yahoo.com', Server: 'smtp.sbcglobal.yahoo.com', Protocol: SMTP, Server Response: '530 authentication required - for help go to http://help.yahoo.com/help/us/sbc/dsl/mail/pop/pop-11.html', Port: 25, Secure(SSL): No, Server Error: 530, Error Number: 0x800CCC78

 

[office politics]

click tools>accounts. select your email account. click properties, click servers, check my server requires authenication.