Absolutely agree. This doesn't fall under the principles of the open internet nor anything in the 'net neutrality' arena. You have no right to expect anyone to receive traffic from your server if they choose not to. It's a major pitfall of running your own relay, but it's not unethical.

Unfortunately 50% of the world's mailboxes are hosted by 2 companies. That means the open internet is far as email goes is already dead in practical terms for most people. When they block another host that host no longer has email network access.

> These blocklists are employed by the actor receiving the email.

If I send an email to [email protected], Alice is the recipient, not Bob the sysadmin for example.com.

This is incorrect. The service you are sending the mail to (example.com in this case) is receiving that mail. They are then delivering it to the user, or not, depending on the agreement they have with the user. If example.com and a user of example.com have agreed that example.com is responsible for providing spam filtering, then they would be remiss in delivering the email to their customer.

This is the way that email is designed to work and the fact that users and service providers have choice is a feature, not a bug. If you don't want your service provider to do this type of filtering, that is your choice. But you have absolutely no right to say that Alice can't get the service she wants from example.com because it's inconvenient for you.

Edit: and just to head off the inevitable "but what about if it's at work and I can't change providers", the domain and email accounts belong to your employer, not you. You are welcome to work somewhere else if you don't like how they configure their systems.

I'd hardly say this is a feature. It's an artifact of the fact that once upon a time computers were expensive, so many people had to share a server with multiple email accounts, and a netop had to run this server. The fact that Alice is beholden to example.com helps nobody but example.com. In an ideal world, Alice would not have to couple her infrastructure with a blocklist and Alice would have the choice of blocklist herself.

Spam is inevitable. Opining about ideal worlds is fun, but it's also irrelevant because that world is gone and it will never come back because it can't.

Alice is not beholden to example.com, she can use any hosting provider she wants. Moving providers isn't even that difficult. It's also totally irrelevant, because again spam is inevitable.