Gajim can't answer link-local XMPP to GNOME3 Empathy/telepathy-salut
We start with sending a message from an Empathy/telepathy-salut Machine (Debian 7) to a Windows machine (Gajim 0.16.1-zeroconfv6_2 on Windows 7).
The Empathy machine is keeping a connection to the Windows machine open indefinitely. When the user tries to send an answer message, the Windows machine is opening up a new connection, on which both sides exchange XML (Gajim sends: from="userA@WINHOST" to="userB@EMPATHY", Empathy sends: to="userA@WINHOST" from="" (!)). Then the Empathy machine is sending "<stream:features/></stream:stream>\n" in a TCP ACK + Push + FIN packet, and both sides close the connection again.
Gajim is not putting the sent message into the scrollback buffer (as it wasn't sent), and not giving out some error/warning either. Neither a timeout after some time.
Perhaps Empathy/telepathy-salut doesn't like a second connection being opened for the same link-local contact? But Gajim does not seem to handle the immediately closed connection well. In either case, there is a work-around:
When the user sets the Local account to offline and then to online again (which clears the open connection from Empathy to Gajim), a message can be sent again to the Empathy/telepathy-salut machine.