perldoc -l Mail::Internet returns 'No documentation found...'
I did not see any output from the print Dumper lines.
perllocal.pod does have an entry for Mail, actually it has more than one since I have installed it a couple of times. The entry (excerpt) is as below:

=head2 Wed Sep 2 13:11:10 2009: C<Module> L<Mail|Mail>
=over 4
=item *
C<installed into: /usr/lib/perl5/site_perl/5.8.8>