Specifies servers, users, and groups that are denied access to a specific server port. The <port> parameter indicates the name of the port you enabled in the Port Setup dialog box and in the Server document. An asterisk (*) represents everyone listed in the Domino Directory. An asterisk followed by a view name represents everyone listed in that view of the Domino Directory. An asterisk followed by a slash and a hierarchical certifier's name represents everyone certified by that certifier.
The users in the Terminations or the Denied_Access group cannot access the SPX port.
It's counterpart Allow_Access_<Port> allows access, however if ONE of these two is set, it automatically restricts the other. Which means once the Allow or Deny are set, only those count. Deny will allow every thing else, Allow will deny everything else.
IMPORTANT NOTE: Use the FULL CANONINICAL Name for all names you specify.