> By simplifying the stack to the above, eliminating SPF, DKIM, and DMARC (and their respective configuration options), and standardizing on one record (MX2) for the future, running your own self-hosted email stack would become much easier. Additionally, the additional authenticity verifications would hopefully allow spam filters to be significantly less aggressive by authenticating against domains instead of IPs.

This assumes that the reason antispam tools make it hard to host your own email is because of spam. That’s only part of it. The other part is that deliverability is a cartel, and two of the biggest players, Google and Facebook/Meta, wish to be the intermediary between you and your audience and sell you access to their eyeballs.

Truly federated email allows you to communicate directly with your audience, bypassing apps and paid ads. This is a threat to their business models.

Additionally, domains are cheap, and moving the trust decision to domain from IP doesn’t get you much. Unknown/fringe domains will still land you in spam by default, same as non-deliverability-cartel IPs do today.