Basic internet security

So I would like to set up my own microcontroller to monitor my doors and windows and email me every time they are opened. Kind of like ADT with with their wireless window sensors. They have be in sleep mode on the door.

I don't predict that this would happen that often. Say no more than 1 Hz. What is the lowest-power way to connect these switches to the internet? It doesn't have to use Arduino + ethernet shield if there is a cheaper way.

WiFi and Bluetooth, while options, are insecure.


Wired ethernet would have to be located and cut.

Sorry, not sure on price, but very confident regarding security.

Hope this helps your decision.