/usr/share/perl5/Mail/Box/Locker/ is in libmail-box-perl 2.118-1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/perl5/Mail/Box/Locker/DotLock.pm
/usr/share/perl5/Mail/Box/Locker/DotLock.pod
/usr/share/perl5/Mail/Box/Locker/FcntlLock.pm
/usr/share/perl5/Mail/Box/Locker/FcntlLock.pod
/usr/share/perl5/Mail/Box/Locker/Flock.pm
/usr/share/perl5/Mail/Box/Locker/Flock.pod
/usr/share/perl5/Mail/Box/Locker/Multi.pm
/usr/share/perl5/Mail/Box/Locker/Multi.pod
/usr/share/perl5/Mail/Box/Locker/Mutt.pm
/usr/share/perl5/Mail/Box/Locker/Mutt.pod
/usr/share/perl5/Mail/Box/Locker/NFS.pm
/usr/share/perl5/Mail/Box/Locker/NFS.pod
/usr/share/perl5/Mail/Box/Locker/POSIX.pm
/usr/share/perl5/Mail/Box/Locker/POSIX.pod