cannot send mail or news with OE
 

I have endured doing without OE for some time because I cannot send mail or
news posts. I am running Windows XP, have AVG Antivirus software and have a
program called Yenc for decoding some newsgroup downloads. I have disabled
the Email Antivirus process within the AVG control panel and I have
intentionally not run the decoding software and have the correct server noted
within the accounts/ mail/servers/properties portion of my OE accounts setup.
I am contacting through the web based server because I cannot send. Thank
you, in advance, for any assistance in re-newing my sending capabilities.
When I run a test email, I recieve this message:
The message could not be sent because one of the recipients was rejected by
the server. The rejected e-mail address was '.
Subject 'Test', Account: 'pop3.highstream.net', Server:
'smtp.highstream.net', Protocol: SMTP, Server Response: '553 sorry, that
domain isn't in my list of allowed rcpthosts (#5.7.1)', Port: 25,
Secure(SSL): No, Server Error: 553, Error Number: 0x800CCC79