Transferring large amounts of data is a problem to overcome for all the IM networks.
You see: Usually you don’t transfer files over the central IM server because it will use the IM providers bandwith which is better used sending out those small text messages. That’s why files are usually transferred in a P2P fashion.
The problem here is that usually there’s a NATing router or even a firewall working at one, or most of the time both ends of the communication. This usually forbids the making of a direct connection – at least without some serious trickery (warning: PDF link) going on
This is why I never expect a file transfer to work – even when using the native IM client.
And today, a guy sent me some image. Via Jabber. Via PyMSN-t.
Just when I wanted to write that it’s never going to work, I watched the bytes flow in.
I’m still unable to belive it: Wildfire/PyAIM-t/Psi succeeded in making a direct P2P file transfer happen from a friend in MSN to my PC running a jabber client.