+foreach my $vn (sort { ksmap($a) cmp ksmap($b) } keys %o) {
+ my $val= $o{$vn};
+ die if $val =~ m/\n|\r|\t/;
+ $metadata .= "$vn\t$o{$vn}\n";
+}
+
+my $mdpart= MIME::Entity->build(Top => 0,
+ Type => 'text/plain',
+ Charset => 'utf-8',
+ Disposition => 'inline',
+ Encoding => 'quoted-printable',
+ Filename => 'metadata',
+ Data => $metadata);
+$mcontent->add_part($mdpart);
+