Unexpected Server response when emailing...

I was wondering if anybody has had any problems emailing using Win 2003 Server? I am running a third party utility and it works off of Outlook. I can email through Outlook ok, but when using this third party utility I receive an error.

Everything is set up, but when I send through this third party utility I receive the following message.. Unexpected Server Response. Is this some type of security problem? Do I need to go into Win 2003 Server settings and fix something?

Any help would be appreciated.

Thanks!

 

What is that kind of utility? Have this utility some email account associated?
What email server are you using?