[iggldiggl]

From a quick read, hey.com still allows arbitrary people to message you and just initially puts them in "The Screener", which doesn't seem like quite the same thing as an absolutely "completely whitelist (opt-in to receive messages) basis".

That's fine by me because

a) I do want to give out some sort of contact info on my homepage and people being able to message me in relation to that (and putting up a contact form leads to its own spam problems), and

b) if you happen to swap contact details offline, you then have to remember that you still need to additionally whitelist that person inside of that message service, which also seems somewhat of a hassle.

Somebody who gets inundated in unwanted messages might have a different opinion on that subject, though, and might indeed prefer a strict opt-in mode, with no exceptions…