If he was out on Friday and then Monday is a holiday, perhaps he is away for the entire extended weekend?

... like hopefully at an intense "learning how to communicate via email" seminar...

I know that being able to talk with him via email during your time away has been a concern for some time. Maybe when you get back to seeing him, it's time to start ironing out the details of how that will work so you'll know what to expect. And maybe you two could 'practice' now before you go?

Can you put a "read receipt" on your email you send so you'll know that he has opened it?