bellsouth.net email not sending

I configured windows mail with few POP3 accounts along with an email address from bellsouth.net. The problem is I am not able to send any email using my bellsouth.net. When I contacted them for help they analysed and said that the problem is from windows mail end and I need to contact Microsoft for the same. Now I don’t know how can I contact Microsoft hence came here.

This is the error I’m receiving while sending mails:
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 'bethandnoahcampbell@yahoo.com'. Subject 'Re: hey', Account: 'mail.bellsouth.net', Server: 'mail.bellsouth.net', Protocol: SMTP, Server Response: '550 [PERMFAIL] yahoo.com requires valid sender domain', Port: 25, Secure(SSL): No, Server Error: 550, Error Number: 0x800CCC79

Hope you guys will help me getting rid of this. Thank you.

I have a small doubt in this. Were you connected with Bellsouth Internet connection when you received this error? Meanwhile also check if your ‘From’ address is valid and working. Reply so that I can get to the cause.

Thanks a lot for your reply Bollea. Yes I was connected with the Bellsouth and I only use Bellsouth’s internet connection. There is no other. Also the From address is valid.

Any other help?

Most of the time such error occurs when people ravel with their laptop and use various ISPs. Server settings gets changed and those error occurs. If that is not in your case, just Open Windows Mail, go to Tools > Account > your email Account > Properties. Now click on general Tab and confirm your email address by typing it correctly again.