Hi, the preferred way to fix this nowadays is to fork https://gitlab.com/apparmor/apparmor, edit files in profiles/apparmor/profiles/extras, commit, push a branch and follow the instructions that `git push' will provide to submit a merge request.
I guess that replacing all relevant occurrences of: /usr/lib/postfix with: /usr/lib/postfix{,/sbin} … should to the trick :) Cheers, -- intrigeri