So we are going to have the Email-Problem sooner or later. Sending Spam is for free and infinitely scalable.
In order to combat this, we need to add friction to posting. The most obvious solution here is to add transaction cost in addition to moderation.
“you can only send me a message if you pay me 1ct” for example.
In systems like Twitter this was a hidden cost layer that active background moderation fixed, which is why Musk’s X is overrun by spam.