/usr/share/man/man1/sylpheed-claws-gtk2.1.gz is in claws-mail 3.8.0-1ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/man/man1/claws-mail.1.gz
/usr/share/man/man1/claws-mail.1.gz