I can show you correspondence that will prove what I am saying.

I refused to enter into any correspondence (ie exchange letters) with him about it.

But it says "communications security, and specifically bandwidth protection [from both friendly interference and adversary action] is imperative.

What if you now need a new communication mechanism or change to a data schema?

But nowadays, with modern communication, we work all the time - in the car, in the coffee shop, at the airport - and are dealing with an influx of personal communication, too.