Suzune

Here is also Et Cetera: https://en.wikipedia.org/wiki/Et_Cetera_(manga)

I’ve been using Sieve on Dovecot (Pidgeonhole) for years and it’s great. Earlier I had Procmail, which is fine, too. The only disadvantage is that I’d need to login on my server to edit the rules, while Sieve is directly editable in email clients.