Hello-
I recently reconnected with someone I knew in grade school and had not seen since then. I asked to join his network and he graciously accepted. He is a C-suite executive at a Fortune 50 company and I imagine, pretty busy.
I am working on building my network, since I am woefully aware of its inadequacy. I imagine knowing this person better would lend itself immensely to that end.
Is there some protocol to establishing some periodic communication with this person? I mean, should I just start emailing (Ctrl+Shift+K--Ctrl+G) and inquiring about his life?
Would an email from out of the blue be welcome? I imagine he is savvy enough to figure out why I reached out to him. He was a few years ahead of me in school but was always kind. I would genuinely enjoy getting to know him. Along with building my network.
I guess my question is: would I be out of line in sending a "How you doin'?" email?
Content suggestions are also welcome.
Thank you.

I can't see why your old
I can't see why your old friend would be upset at all if you sent an email (particularly via LinkedIn) asking how he has been doing and re-establishing your relationship. The only thing that would turn me off were I in his shoes would be you sending that email and in it asking about a job or for my help so soon.
Best of luck.
That's part of what social networks are for
Part of the reason we used LinkedIn is to be able to stay connected to our network and to reconnect with people we've known in the past. If this man is someone you genuinely respect and you want to get to know him better then yes, go ahead and send a 'how are you?' email. If you are physically located nearby then you could also suggest getting together in person when he is available.
Good luck!
As M&M often say, we ascribe
As M&M often say, we ascribe behavior to people based on our own misconceptions. You are, of course, correct.
Unfortunately we do not live near each other. I think it would be easier if I could offer to get together.
Thank you both for your input.
M Nikolic