@Tomáš Janoušek no shame in that. Pick your battles. Big mail sure screwed small mail over all these years.
I've looked at stalwart but it's alarm bells all over. Way too complex. I've always had a complete aversion of email stored in databases.
Postfix and dovecot have been good over the 25 years I've run them, with spamassassin thrown in. I don't receive much spam anyway so it's not working hard. It's a pretty hands-off operation really.