Not to oversimplify the issue... but you could probably run a small VPS and SMTP relay service that requires tls+auth and just relays all email from your domain through to API calls. You could probably get something operational in a couple hours with Claude Code.

My first thought in reading this would be using this service and the default mail app's structure to back end typical email protocols so you can still use a regular email client to access/use the system as a gateway.

That said, I still think Cloudflare is in a unique position to compete with gmail/m365 mail/calandar/contacts... possibly funding Thunderbird development to tighten the integration as a mail client.

For that matter, I still think cloudflare is in a good position to create a new

Oh yeah for sure. At that point, using SES is probably a better option compared to running a VPS just for SMTP. I posted that to let them know that SMTP support is a requirement for some developers.