...could you advise if it is actually possible to use both before-queue and after-queue filtering? Reindl surely but how does that make sense?
It makes because it will use two filters, not just one. It will filter before queue first and then anything that may be missed or let through on purpose will be filtered after queue by the second filter.
Since it is the Dovecot list I would be curious to know how to do it Dovecot Sieve way.
doing *what*?
Making two filters work together (dovecot after-queue and postfix before-queue).
That is my Postfix passes it over to Dovecot for delivery but all the milters work with Postfix directly and my passing delivery over to Dovecot should theoretically simply disable any before-queue filters
that's just impossible
It is technically and theoretically impossible as far as I understand but I thought that I also could be wrong at some point and there were ways to arrange it somehow... that’s why I asked away.
you can't control a before-queue filter that way because, well, he is before-queue and has no idea what later happens with that message.
I wouldn’t care what the before-queue would be up to as long as they would "cooperate" together with the after-queue one. That is I would create different rules for "before" and for "after" filters making sure that the rules do not clash, conflict, or contradict with each other in any way. But then again my delivery is done by either Postfix with filters or Dovecot with filters and I am unable to use both. That's actually how my current settings on this server I was setting up work. Postfix uses its regexp header_checks without any filters and it works just fine, then it is passed over to Dovecot for delivery where Spamassassin filters kick in and do their job on top. Thus I have two "spam stoppers" so to speak. The advantage is that I can use both regexp / pcre in Postfix and sieve scripting in Dovecot Sieve.