use Encode qw(encode);

    my $message = "Message with spéciâl characters";

    my $msg = MIME::Lite->new(
        'From'      => encode('MIME-Header',$emailReturn),
        'To'        => encode('MIME-Header',$email),
        'Subject'   => encode('MIME-Header',$subject),
        'Type'      => 'text/html',
        'Data'      => $message,
    );

    $msg->attr('Encoding' => 'quoted-printable');
    $msg->attr('content-type' => 'text/html');
    $msg->attr("content-type.charset" => "windows-1252");
    $msg->send('smtp', "IP ADRESS", Timeout=>60);