FreeIPA VS Dovecot

I also want to try FreeIPA but as it's built on top of 389ds I'm afraid that it's gonna be as big of a memory hog (will try it later anyways) and has many things I don't and won't need, which I'm afraid would add complexity to setup.

FreeIPA server and replicas

A good place to start might be FreeIPA.

FreeIPA1 is not written in PHP. I believe you are confusing it with another project, maybe FreePBX which is written in PHP?

I had Fedora 34 installed to an SD card for a FreeIPA node which worked well. It was most likely an earlier release (32 or 33) running on a Pi 3B which would occasionally run out of memory, so the whole thing got transplanted to a Pi 4 with 4GB. I'm pretty sure I used the disk image to install since I like to start from a minimal image and only install what I need.

Take a look at FreeIPA

https://www.freeipa.org/page/Main_Page and https://github.com/freeipa/freeipa/tree/master/doc/workshop

Mail server using Postfix, Dovecot, and Rspamd

Eventually I will set up Dovecot as a local IMAP server, pointing to that Maildir. When I've done this before, I've set up a self-signed certificate so Apple Mail wouldn't complain.

You might want to use dovecot for this if I understandyou correctly

If you really want to try it (and keep it up to date for security fixes, check and handle any relay issues or possible spam attackers) then look at Dovecot or Kerio

An IMAP server. I have a strong preference for dovecot for this.

I'd do it with a local IMAP server in conjunction with a webmail client that connects to it. Dovecot is a fantastic and easy to use IMAP server. Webmail clients are a pretty personal thing, but the last time I used Roundcube it seemed pretty good.

For the record, I'm using dovecot (https://www.dovecot.org/) for IMAP and Haraka (https://haraka.github.io/) for SMTP.

self hosting mail is always a pain and can take up a lot of support time and you really need to know your stuff. I always use Plesk witch configures Dovecot. But if there is anyway you can push them to use an external service you should do that.

I run a mail server on DigitalOcean for a few domains using a fairly standard FreeBSD setup running dovecot and postfix. If you're set up your preferred stack on another hosting provider before, you're aware of all the pitfalls: