> every website asks you to check the spam folder if the verification mail

This is not a registration email that you expect to receive after clicking somewhere on a website.

This is the kind of email that says "something important happened to your account you may not be aware of, you should really know this; if it wasn't you, you are now in danger".

(Of course in this case it was me, but the whole purpose of this type of email is to alert you promptly in case it wasn't you.)

Does it make sense to send such vital notifications via a channel that can silently hide them? This is ideal for mobile push notifications, and if you want reliable notifications, you should install the PayPal app.

An unsolicited email is not going to get noticed in the hundreds of spam emails I get on a weekly basis (currently 189 since February 3).