When migrating away your chat system, from Google Apps to hosted.IM, you may face some issues.
During the last two months we have received feedback from hosted.IM users reporting problems to federate with Google. Then we have discovered a common pattern on all these scenarios: their XMPP domains were formerly served by Google Apps.
Where the problem lies
Although this problem was already documented on our FAQ , this time it was different. Even if you disable XMPP and remove your domain from Google Apps , you will experience problems to add Gmail users or see their presences once your domain was hosted on a different server. hosted.IM is one of the possible cases, but it will also happen if you choose to run your own XMPP server .
Apparently, Google’s effort on infrastructure optimization lead to this issue. It seems they use an internal routing mechanism for domains hosted within their cloud and former domains are not cleaned out completely once removed.
We hope Google will find a successful solution to this problem. In the meantime you can report this problem on Google forum .