Yes! It works now
May 09 14:00:54 s2sin5644f1628700 debug connection pubsub.beta.kontalk.net->domain.de is now authenticated for pubsub.beta.kontalk.net
May 09 14:00:54 s2sin5644f1628700 info Incoming s2s connection pubsub.beta.kontalk.net->domain.de complete