I have been after something similar to do both spam filtering and email organisation.
This one seems like it ticks the right boxes as well as the others commented
https://docker-mailserver.github.io/docker-mailserver/edge/config/advanced/mail-sieve/
The alternative if its just email filtering you could setup Thunderbird in a docker container so it runs 24/7 and you have a GUI to do your rules. So regardless of which other app you are using they get sorted assuming it gets them first.
I have been after something similar to do both spam filtering and email organisation.
This one seems like it ticks the right boxes as well as the others commented
https://docker-mailserver.github.io/docker-mailserver/edge/config/advanced/mail-sieve/
The alternative if its just email filtering you could setup Thunderbird in a docker container so it runs 24/7 and you have a GUI to do your rules. So regardless of which other app you are using they get sorted assuming it gets them first.