It works fine since it looks after the colon ( : ) for the @ then the host.
So an @ before the ( : ) is ignored.
Trying to set deepbit as backup, but how to do it, when username contains @? Eg --backup=abc@gmail.com:password@pit.deepbit.net:8332 won't probably work, because it thinks that "gmail.com:password@pit.deepbit.net:8332" is the whole hostname?