THIS IS NOT A TOPAZ ERROR. THIS IS A SERVER CONFIGURATION ERROR
Form http://www.christensen-software.com/knowledgebase.htm
What can I do about the error message "Host did not acknowledge DATA
command [554. 5.5.2 No valid recipients]"?
If you are using Exchange 2000 Server you might want to check the
following settings:
Are all recipient domains you want to support added to the
default policy in the recipient policies in your Exchange
configuration? Check out our Exchange 2003 and Exchange 2000
configuration guide, Part 1. Make sure that the check mark left
of the domain in question is there as well.
The relay rights in the virtual default SMTP connector: You
need to give the machine that runs POPcon (even if it is the
same machine that runs Exchange 2000 Server) RELAY RIGHTS. This
is because often your ActiveDirectory domain will not be the same
as your email domain (name).