[Wah cloak on]
Email uses the internet to traverse between endpoints. This is a system that has no controls, no built-in encryption, and is manned by who-knows.
The switches and routers that make up the core of the internet can be programmed to copy off the content passing through them. All it takes is a spotty IT wallah to do that. Spotty IT wallahs don't get paid very much. It doesn't take the brains of an Archbishop to figure out that they can be bribed.
If N727NC has used the same login credentials for his internet banking, it might go horribly wrong for him, and he's right to raise this as a concern.
[/Wah cloak]