> > exim -> postfix
>
I'd like to suggest that Debian' use of a lightweight EXIM (not the
full EXIM) remain the default over Postfix.

I've managed and programmed Postfix servers before. It is not a
trivial task, nor do I believe that Postfix makes a best
replacement.

Postfix has several longstanding quirks that can be very annoying or
even problematic, especially when dealing with domain redirection or
email address resolution.

For example when using lists:

bob@??? bob
bob@??? bob2


The correct behavior standardized by sendmail and common sense is that
email for those two addresses is distinct. Postfix will only look for
the best, first match. So emails that should go to the bob2 account
end up in "bob" instead.

I do not know the Postfix devs have ever corrected this, I've been
out of the server business for some time. If they have great, but I
still think that Debian's choice over Postfix was the right call.
There is a lot less to go wrong than with Postfix.

T.J.