You should not negotiate via email because you cannot control tone or timing, which can lead to negative interpretations of your request.

“So I might email you my demands demands, right? Or my negotiation. And the problem with that is I can't control tone. I can't control, especially when you're negotiating at high levels. If I push back and the CEO that reads it's in the airport security line and pissed off and they read it, they migh”