[tdrdt]

I run my own email. But I think it is a software problem.

It would be nice of you could just install an email program that will set all the right settings for you. DNS, database, roles and rights, certificates, firewall and so on.

There is server management software that can do this but then you have the same problem: it is just complicated for most people.

[pmlnr]

There is such thing: https://maddy.email/