Publishing exchange with UAG

Hello all,

Greetings!!!

Can any one suggest me about exchange server publish on UAG server.My question is :-

Is it possible to publish our 3 exchange servers(OWA) which are not in our forest(these are out side from our forest and there is no trust relation between our domain and other domains though we are able to connect to them)on UAG server?

Thanks in advance!!!

Prateek