We are also looking to migrate off Cloudflare. I thought Bunny.net was mostly a pure CDN, not a reverse proxy like Cloudflare. Am I wrong? One of the most important things for us would be DDoS protection.
Self Plug-in: We are currently beta testing Hyvor Relay [0], a self-hosted alternative for sending emails. We are focusing more on observability (monitoring DKIM/SPF, periodically querying DNSBLs) and DNS automation.
A simple docker compose up can get a reasonably working setup [1]
We are working on an open-source, self-hosted solution [0] to make this easier. When you correctly set up DKIM, SPF, reverse/forward DNS for IPs, it is not much hard to get emails delivered. IPs can still get blacklisted and you need to monitor blacklists and contact them if it happens. Solutions like Postfix are great, but they lack observability. In our solution, we have developed dashboards and health checks to make it easier to find problems with the set up.
We are currently running beta tests (really appreciate it if you can join).
For the past two months, I have been working on Hyvor Relay [1], an open-source, self-hosted alternative to AWS SES, Mailgun. It's been an awesome ride learning SMTP and DNS in depth. And, we're pretty close to a beta release.