The last time I started to register I read the terms and they wanted me to bind myself to terms that they could unilaterally alter and still bind me!

I sent them a note and received a nice phone call from a person that assured me they would never do that. Very impressive customer service, but thank you, no.

To be fair, this was probably 10 years ago and they may have a new policy.

It's a good bet it's not enforceable. The lawyers tend to be paranoid because it can help, and hurts very little (you're a minority).

I registered years ago, I can't even remember how long ago (5 years+ I'd guess, maybe even 10). I have not gotten a single email from them.

I don't understand why they want the registration, but at the same time it's not problem to do it.

I am speculating here, but I suspect it gives them a metric that is in some ways more reliable than just measuring unique IP addresses.

Most likely it is that metric they really want, but if you want to be cynical, they could be selling those addresses without ever sending a single message themselves.

It's a unique email address that no one else has. It has never received email.

I get mail from them but it is really quite infrequent. Perhaps it ends up in your spam folder?

Sorry for the stupid suggestion but Have you checked in your spam box?