/usr/share/perl5/Mail/Message/Convert/ is in libmail-box-perl 2.120-1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/perl5/Mail/Message/Convert/EmailSimple.pm
/usr/share/perl5/Mail/Message/Convert/EmailSimple.pod
/usr/share/perl5/Mail/Message/Convert/Html.pm
/usr/share/perl5/Mail/Message/Convert/Html.pod
/usr/share/perl5/Mail/Message/Convert/HtmlFormatPS.pm
/usr/share/perl5/Mail/Message/Convert/HtmlFormatPS.pod
/usr/share/perl5/Mail/Message/Convert/HtmlFormatText.pm
/usr/share/perl5/Mail/Message/Convert/HtmlFormatText.pod
/usr/share/perl5/Mail/Message/Convert/MailInternet.pm
/usr/share/perl5/Mail/Message/Convert/MailInternet.pod
/usr/share/perl5/Mail/Message/Convert/MimeEntity.pm
/usr/share/perl5/Mail/Message/Convert/MimeEntity.pod
/usr/share/perl5/Mail/Message/Convert/TextAutoformat.pm
/usr/share/perl5/Mail/Message/Convert/TextAutoformat.pod