/usr/share/doc/gosa-plugin-mail/Changelog.gz is in gosa-plugin-mail 2.7.4+reloaded2-9ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/gosa-plugin-mail/changelog.gz
/usr/share/doc/gosa-plugin-mail/changelog.gz