I get following message when try to send email to my email.

When trying to deliver your message, the mail server at host=mail.proagentwebsites.com/proagentwebsites.com,from=mail.proagentwebsites.com encountered problems with the following addresses:

For <steve.hanson@colorado-re.com>, Site (colorado-re.com/74.201.154.201) said: 550 5.1.1 <steve.hanson@colorado-re.com>... User unknown

For a more detailed explanation see http://netwinsite.com/surgemail/deliver_failed.htm