POP3 Server Problems with Insight/Road Runner

I have been using the POP3 server from long time but after upgrading to Vista it has completely stopped working. The error that I get is written below

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 xxxxxxxxxxxxxxx. Subject '', Account: , Server: 'smtp-server.insight.rr.com', Protocol: SMTP, Server Response: '550 Invalid recipient: <abcd@insight.rr.com>', Port: 25, Secure(SSL): No, Server Error: 550, Error Number: 0x800CCC79

I need help?

I think that it might be possible that the account with that email address may no longer exist. Did you make sure that the connection to the outgoing mail server cross from one of the internet provider's equipment to another's? If it is so then the port 25 are often blocked to cause trouble for spammers. Hope this helps.

I have now solved it by reinstalling my information on my sub-accounts and can now receive and send emails as well. Previously the address was not displaying but when I deleted my information with Roadrunner and again re-entered all the new information then the problems were in the sub-accounts with error message 0x800ccc79.