Unable to send mail from Live Mail 2012; Error 0x800CCC79

I have been using Windows Live Mail 2012 (Build 16.4.3505.0912) for over a year at least. I am a Time/Warner Road Runner customer and I use Live Mail in conjunction with the T/W mail server. Last night I discovered that I was not able to send mail from my Live Mail (WLM) program to the Time/Warner mail SMTP server (TWC). I am however able to receive mail from the TWC POP3 server.  I am running Windows 7 Home Premium with Service Pack 1.

I have verified with Time/Warner tech support that my mail settings are correct.



I can send mail from my web based mail box to my WLM desktop application and any mail that comes to my e-mail address *** Email address is removed for privacy *** is forwarded to WLM. However when I try and send mail from WLM to the SMTP server I get the following error message

The message could not be sent. The setting for your outgoing email [SMTP] server might need to be configured. To find the server settings for '*** Email address is removed for privacy ***', please contact your email service provider.

Subject 'A New Test Message'
Server Error: 451
Server Response: 451 Outbound mail refused - 72.182.74.224 - See http://www.timewarnercable.com/en/residential-home/support/topics/internet/email-setup.html [R0209002]
Server: 'smtp-server.austin.rr.com'
Windows Live Mail Error ID: 0x800CCC79
Protocol: SMTP
Port: 25
Secure(SSL): No

TWC tech support believes that, from their end, all settings are correct. We even tried an alternating SMTP server and port: