A plug for a mailing list I've subscribed to:
It's called "MissionBytes" and it "is geared towards people in the technological world who are already mission-minded but either do not have a familiarity of computers in missions, who want to broaden their understanding, or who simply want to see some the things we see as we work with different organizations."

You can subscribe at:
https://storm.lightsys.org/secure/mailman/listinfo/missionbytes
You'll need to accept their certificate as they haven't got a "proper" one, so you'll have to trust me that they are good people :-)

It's not a discussion list, but more of a occasional news item list, so you won't get overwhelmed with emails from the list.