[hirako2000]

We call it the email mafia.

To send emails we need to pay for a mail service. Or get ads of course Gmail is part of the ring.

Like most things it start with good intentions, to fight spam. As if it even worked, I guess we would get far more without they will say.

[calvinmorrison]

It's one of the downsides of decentralized networks. Trust is built or pay-your-way-into'd.

[AnthonyMouse]

This has nothing to do with decentralized networks. It's simple incompetence.

If you haven't received any mail from a mail system before (or in a long time) and then it sends you one message, it probably isn't spam, because spammers are typically going to send you a large number of messages. You also typically want to let the first few messages through so the recipient can see them and then classify it as spam or not, so that you get some data on how to treat future messages from that sender.

This is the same thing a centralized system should be doing with individual users. You impose some reputation on accounts (e.g. by sender/registration IP address) and then if that address starts spamming people it gets blocked, and otherwise it doesn't.