AnsiMail VS docker-mailserver

I like their pricing structure for bulk accounts. What I'd absolutely love to see is more email services that are Protonmail compatible, utilizing WKD or whatever it they need. Here's something to look at anyway https://github.com/Excision-Mail/Excision-Mail

It's not trivial, but it's doable.

Excision Mail which runs on OpenBSD hits the majority of what you need technically. https://github.com/Excision-Mail/Excision-Mail

The bigger problem is finding a hosting provider that hasn't had their entire space blacklisted.

For that, you're likely going to have to pick a "responsible" provider, have a couple of rounds of back and forth with them to prove you're neither an idiot nor a spammer, and ask them to manually open the port for you. And they're going to demand something that will tie to identity.

I have used Roundcube docker-compose-fpm.yaml, which looks like it can be easily extended with docker-mailserver

However... For a live fire, in production setup I would push people to use a meta package like docker-mailserver, mailcow, mail-in-a-box or modoboa as it's better to have someone else set the sane defaults to prevent you from missing that one line in you config.

Se proprio vuoi farlo per il gusto di riprendere familiarità con i vari concetti, giocherei con dei set di container docker tipo https://github.com/tomav/docker-mailserver (su GitHub ne trovi molti altri, alcuni tipo mailcow anche con GUI per gestire il grosso delle opzioni).

Yes, spam learning is documented on the Wiki.