Procmail (or the custom binary) was removed or replaced by a stub that returns a non-zero exit code. Many distributions removed Procmail by default after 2020.
grep -E "^dovecot" /etc/postfix/master.cf Output example: Procmail (or the custom binary) was removed or
The filter binary was recompiled but its dependencies (e.g., Perl modules, libssl) are now incompatible with the version Postfix is trying to run. increase Postfix’s global verbosity:
dovecot unix - n n - - pipe flags=DRhu user=vmail argv=/usr/libexec/dovecot/dovecot-lda -f $sender -d $user@$domain -o plugin/quota=maildir:User quota -d Also, increase Postfix’s global verbosity: Procmail (or the custom binary) was removed or