/usr/share/perl5/Mail/Message/Body/ is in libmail-box-perl 2.120-1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/perl5/Mail/Message/Body/Construct.pm
/usr/share/perl5/Mail/Message/Body/Construct.pod
/usr/share/perl5/Mail/Message/Body/Delayed.pm
/usr/share/perl5/Mail/Message/Body/Delayed.pod
/usr/share/perl5/Mail/Message/Body/Encode.pm
/usr/share/perl5/Mail/Message/Body/Encode.pod
/usr/share/perl5/Mail/Message/Body/File.pm
/usr/share/perl5/Mail/Message/Body/File.pod
/usr/share/perl5/Mail/Message/Body/Lines.pm
/usr/share/perl5/Mail/Message/Body/Lines.pod
/usr/share/perl5/Mail/Message/Body/Multipart.pm
/usr/share/perl5/Mail/Message/Body/Multipart.pod
/usr/share/perl5/Mail/Message/Body/Nested.pm
/usr/share/perl5/Mail/Message/Body/Nested.pod
/usr/share/perl5/Mail/Message/Body/String.pm
/usr/share/perl5/Mail/Message/Body/String.pod