$generierte_daten = do_generate_file();

$msg = MIME::Lite->new(
                 From    => 'me@example.com',
                 To      => 'you@meomy.com',
                 Subject => 'Deien Datei',
                 Type    => 'TEXT',
                 Data    => "Anbei die Datei"
                 );
$part = MIME::Lite->new(
                 Type     => 'text/plain',
                 Data     => $generierte_daten,
                 );
$msg->attach($part);
$msg->send;