The goal is to allow easily moving away from an email provider e.g from protonmail to tutanota or fastmail or whatever. How do people achieve this?
I just want to have myname@mydomain, the emails to go to whichever managed email service that allows it, and to then grab everything from that service with POP to then self-host a proxy that multiple devices can connect to. STMP can go either to my hosted server or the managed host, doesn’t matter.
The idea is explicitly not to do the job of a managed email service. No DKIM, no SPF, no DMARC, none of that.
Distro is NixOS, but can adapt any instructions given. Mentioning just in case somebody already has a nix configuration with this setup.
Best option is probably to look for providers that support custom domains, so you can point your domain directly to their mail servers. This usually require a paid subscription. Upside is that you retain control over your domain without having to host any email server.
The problem is that by putting a mail relay in between, while technically possible will break the SPF and DKIM chain for all emails that you forward. I don’t think there is a good way around this since they check against the senders domain (and assuming that you can’t get the email provider to trust your relay server)