Question : "553 Sorry, that domain isn't in my list of allowed rcpthosts"

What am I doing wrong? I configured my smtp default virtual server to send via a smart host but I get this error message.
If  I configure it to send by DNS some messages do arrive at the destination but others don't because since my IP is dynamic some servers will not accept e-mail from it.

That is why getting this smarthost to work is so important.

"Your message did not reach some or all of the intended recipients.

      Subject:      
      Sent:      12-01-2004 23:18

The following recipient(s) could not be reached:

      [email protected] on 12-01-2004 23:18
            There was a SMTP communication problem with the recipient's email server.  Please contact your system administrator.
            "

Answer : "553 Sorry, that domain isn't in my list of allowed rcpthosts"

Use the IP address in brackets in the smart host settings, it's more reliable