I have the problem, that I have a Postfix/Dovecot combination running with Sieve activated. The thing is if I call sieve-filter on the INBOX, I get the information that the mail is to be moved to the appropriate folder. However during delivery the mail is not moved there. Other rules in the script are working so it is installed in general.
You didn't say either way, so this is a guess. Sieve is only ran by Dovecot. If Postfix is configured to deliver mail directly (the default), where Postfix writes the email to drive, then Dovecot never knows delivery happened and doesn't have a chance to run Sieve. Postfix must send the email to Dovecot and let Dovecot save the email to drive in which then Sieve would run. One option to do this is having Postfix deliver to dovecot LMTP. https://doc.dovecot.org/configuration_manual/howto/postfix_dovecot_lmtp/
