New lines (\r\n) are not working in email body

I am using PHP mail() function:

    $to      = 'AAAA <postmaster@xxx.xx>';
    $subject = 'BBBB';
    $message = "CCCC\r\nCCCC CCCC \r CCC \n CCC \r\n CCC \n\r CCCC";
    $headers = 'From: DDD<postmaster@xxx.xx>' . "\r\n";
    $headers .= "Content-Type: text/html; charset=\"UTF-8\"; format=flowed \r\n";
    $headers .= "Mime-Version: 1.0 \r\n"; 
    $headers .= "Content-Transfer-Encoding: quoted-printable \r\n";
    mail($to, $subject, $message, $headers);

When I receive this email it looks like this:

CCCC CCCC CCCC CCC CCC CCC CCCC

I would expect something like this:

CCCC
CCCC CCCC CCC 
CCC 
CCC 
CCCC

It works fine without Content-Type HTTP header. How can I make new lines and still use my "Content-Type" declaration?