>>> Several disadvantages of Exim were discussed in a different thread. So
>>> my question: Why use Exim instead of Postfix or Qmail?
>>
>> This evades me. I have no idea.
>>
>> First thing with any new installation that has Exim on it is to replace it
>> by Postfix.
>>
>> I once heard from someone preferring and using Exim that it would be
>> possible to configure it in a more flexible way.
>>
>> I don't know. Whatever I needed so far I could also do with Postfix.
>> Combined with rspamd and Dovecot it is a complete mail server solution for
>> me. Running inside an Incus container on a Devuan based server. The
>> container itself is running Alpine Linux. Works like a charm and I see no
>> reason to change it.
>
> I have long used the courier collection of email servers and stuff,
> originally based on the theory that they are an entire suite that should
> be configured and act the same. Just like you, works fine, no need to
> change.
>
> Even using it on my desktop, though not all of it.
>

I use and recommend courier.
Easy, stable, powerful and coherent mail suite (MDA and MTA).
Postfix has similar good features to courier's MTA, but postfix is ​​just MTA. For
a mail server you need a good MDA, and since the only MDA I recommend is
courier's MDA, instead of configuring postfix + courier-imap it is simpler to
just use courier (MTA+MDA suite).

By the way, the latest version of courier should be packaged for testing.
I have limited time, but I can help.

Best regards.