/usr/share/man/man8/pw2userdb.8.gz is in courier-authlib-userdb 0.68.0-4build1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/man/man8/makeuserdb.8.gz
/usr/share/man/man8/makeuserdb.8.gz