Re: Before I go reinventing someone elses wheel....
I've done something similar with detecting when my well pump comes on.
The email part was pretty straight forward because Linux has a number of
command line email clients.
mutt - email client
postfix - email server
paclink-unix - winlink support
For the AC detection circuit I used a Linrose B2150A3 Amber Neon Pilot light as
an Opto-isolated AC Voltage Sensor. Some links below for reference:
* [[https://forum.arduino.cc/index.php?topic=403547.0 | How to detect AC voltage (not measuring)]]
* [[https://www.hackster.io/porrey/vacsensor-0fe427 | Opto-Isolated AC Voltage Sensor]] - Daniel Porrey
* [[https://www.amazon.com/Linrose-B2150A3-Amber-105-125VAC-Pilot/dp/B008JFSOQU/ref=sr_1_3?ie=UTF8&qid=1439643695&sr=8-3&keywords=Linrose+pilot+light | Linrose B2150A3 Amber 105-125VAC Neon Pilot Light]]
I would run the RPi from 12 Volts using some buck regulator.