Mike Cardwell claims that T-Mobile UK are silently disrupting VPNs and secure connections to mail-servers, using packet-injection techniques more often found in the Great Firewall of China. He documents his findings in detail, and has found someone on the T-Mobile customer forums who claims that a senior technician there stated that it was a deliberate policy decision at T-Mobile to keep mail from being sent through any servers apart from their own.
The consequence of this is that you must communicate over T-Mobile’s 3G network in a way that allows them to snoop on you and read your email. And since 3G security has been compromised for years, it also means anyone within range of your cell tower can also snoop on you. Mike borrowed techniques from those who fight the Great Firewall of China to build a system that lets him tunnel securely and keep his sensitive data secret, but unless you run your own servers, you’re screwed if you’re a T-Mobile customer.