use Mail::QmailQueue;
  use Mime::Lite;

  # generate mail.
  my $mime = MIME::Lite->new(
      #...
  );

  # send mail via qmail-queue.
  my $qmail = Mail::QmailQueue->new;
  $qmail->sender($ENV{USER});
  $qmail->recipient('postmaster@foo.bar');
  $qmail->data($mime->as_string);
  $qmail->send;