See: http://googletalk.blogspot.com/2006/01/xmpp-federation.html
The Google Talk Service uses dialback. The Google Talk Service uses the roster as a whitelist. You must be in the Google Talk user's roster to send messages to the user.
See: http://googletalk.blogspot.com/2006/01/xmpp-federation.html
The Google Talk Service uses dialback. The Google Talk Service uses the roster as a whitelist. You must be in the Google Talk user's roster to send messages to the user.