/usr/share/perl5/Mail/Transport/ is in libmail-box-perl 2.120-1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/perl5/Mail/Transport/Exim.pm
/usr/share/perl5/Mail/Transport/Exim.pod
/usr/share/perl5/Mail/Transport/IMAP4.pm
/usr/share/perl5/Mail/Transport/IMAP4.pod
/usr/share/perl5/Mail/Transport/Mailx.pm
/usr/share/perl5/Mail/Transport/Mailx.pod
/usr/share/perl5/Mail/Transport/POP3.pm
/usr/share/perl5/Mail/Transport/POP3.pod
/usr/share/perl5/Mail/Transport/Qmail.pm
/usr/share/perl5/Mail/Transport/Qmail.pod
/usr/share/perl5/Mail/Transport/Receive.pm
/usr/share/perl5/Mail/Transport/Receive.pod
/usr/share/perl5/Mail/Transport/SMTP.pm
/usr/share/perl5/Mail/Transport/SMTP.pod
/usr/share/perl5/Mail/Transport/Send.pm
/usr/share/perl5/Mail/Transport/Send.pod
/usr/share/perl5/Mail/Transport/Sendmail.pm
/usr/share/perl5/Mail/Transport/Sendmail.pod