does indeed beg the question of trust.
And there are so many ways to communicate it'd be a full time job to monitor them all. ( email' web based mail gmail etc, messenger, face book etc) Not to mention SMS's
If you ever did act upon anything you'd "found out" he'd shut down that line of comms anyway.
Pointless to even try and monitor.
Nope....you're just going to have to learn to trust him and instill a sense of responsibility
Good luck with that . You clearly have issues