Companies do register domains before launching products and don't want to leak them. Now, I still support Microsoft and other companies to list the domains they send official emails from.

Why would that not be possible? You can still do that and then once the rabbit is out add it to the main list. Come on, don't let the good be the enemy of the perfect. I'm sure there are several ways to find and list all domains. What bothers me more is that they allowed to have different domains in the first place. Why not sub domains to make it clear.

That's what I said? Companies can hide domains while they are under development but then they should still maintain a list that they send emails from. I was opposed to legislation that required all registered domains regardless of use being published.