php - PHP メール送信者:「不明な送信者」を示すフルネーム

Question

if(empty($_POST)=== false){
    //send email

    $fullname = $_REQUEST['fullname'];
    $names = $_REQUEST["fullname"];
    $phonenumber = $_REQUEST['phonenumber'];
    $mobilenumber = $_REQUEST['mobilenumber'];
    $postcode = $_REQUEST['postcode'];
    $level = $_REQUEST['level'];
    $creditors = $_REQUEST['creditors'] ;
    $status = $_REQUEST['status'] ;
    $monthly = $_REQUEST['monthly'] ;
    $partner = $_REQUEST['partner'] ;
    $subject="The Debt Advice Service";
    $message = "Full Name: ".$fullname. " \n\n";
    $message .="Phone Number: ". $phonenumber."\n\n";
    $message .="Mobile Number: ".$mobilenumber."\n\n";
    $message .="Postcode: ".$postcode."\n\n";
    $message .="Level Of Debt: ".$level."\n\n";
    $message .="How many debts / creditors: ".$creditors."\n\n";
    $message .="Employment Status: ".$status."\n\n"; 
    $message .="Monthly Income (£): ".$monthly."\n\n"; 
    $message .="Partner's Income(£): ".$partner."\n\n"; 
    $headers = 'From: '.$names."\r\n".
    'X-Mailer: PHP/' . phpversion();

    //$name = $_REQUEST['fullname']; 
    //$headers = "From: $name";

     mail("mymail.com", $subject, $message, $headers);
     mail("mymail.com", $subject, $message,  $headers);
}

出力：

$header単語名を入力すると名前は有効ですが、フルネームを入力すると、送信者は「不明な送信者」と言って問題を解決してください.