/usr/share/perl5/Mail/ListDetector/Detector/ is in libmail-listdetector-perl 1.03+dfsg-1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/perl5/Mail/ListDetector/Detector/AutoShare.pm
/usr/share/perl5/Mail/ListDetector/Detector/Base.pm
/usr/share/perl5/Mail/ListDetector/Detector/CommuniGate.pm
/usr/share/perl5/Mail/ListDetector/Detector/CommuniGatePro.pm
/usr/share/perl5/Mail/ListDetector/Detector/Ecartis.pm
/usr/share/perl5/Mail/ListDetector/Detector/Ezmlm.pm
/usr/share/perl5/Mail/ListDetector/Detector/Fml.pm
/usr/share/perl5/Mail/ListDetector/Detector/GoogleGroups.pm
/usr/share/perl5/Mail/ListDetector/Detector/LetterRip.pm
/usr/share/perl5/Mail/ListDetector/Detector/ListSTAR.pm
/usr/share/perl5/Mail/ListDetector/Detector/Listar.pm
/usr/share/perl5/Mail/ListDetector/Detector/Listbox.pm
/usr/share/perl5/Mail/ListDetector/Detector/Listserv.pm
/usr/share/perl5/Mail/ListDetector/Detector/Lyris.pm
/usr/share/perl5/Mail/ListDetector/Detector/Mailman.pm
/usr/share/perl5/Mail/ListDetector/Detector/Majordomo.pm
/usr/share/perl5/Mail/ListDetector/Detector/Onelist.pm
/usr/share/perl5/Mail/ListDetector/Detector/RFC2369.pm
/usr/share/perl5/Mail/ListDetector/Detector/RFC2919.pm
/usr/share/perl5/Mail/ListDetector/Detector/Smartlist.pm
/usr/share/perl5/Mail/ListDetector/Detector/Yahoogroups.pm