use MIME::Entity;

my $msg = MIME::Entity->build(
    Type     => 'multipart/mixed',
    From     => 'me\@domain.com',
    To       => $recipient,
    Cc       => \@cc,
    Subject  => 'the subject',
    Encoding => '8bit',
  );

  $msg->attach(Data        => $text_message,
               Type        => 'text/plain',
               Encoding    => '8bit',
  );
  $msg->attach(Data        => $html_message,
               Type        => 'text/html',
               Encoding    => '8bit',
  );

  ### Send it:
  open MAIL, "| /usr/sbin/sendmail -t -oi -oem"
         or die "open: $!";
  $msg->print(\*MAIL);
  close MAIL;