How to restrict PHP mail from sending email to spam folder

`I tried the code below but it is still sending to SPAM folder. Kindly help me to figure this out such that emails goes to INBOX only.

function sendEmail($content,$email,$phone){
  $headers = "Reply-To: Danuel <".$email.">rn";
  $headers .= "Return-Path:Danuel <".$email.">rn";
  $headers .= "From:Danuel <".$email.">rn"; 
  $headers .= "Organization:Danuel internationalrn";
  $headers .= "MIME-Version: 1.0rn";
  $headers .= "Content-type: text/plain; charset=iso-8859-1rn";
  $headers .= "X-Priority: 3rn";
  $headers .= "X-Mailer: PHP". phpversion() ."rn";
  $to ="[email protected]";
  $subject ="Number ".$phone." Banned";
  return mail($to, $subject, $content, $headers);
}

if(isset($_POST['send'])){
    $content='Hey';
    
    if(sendEmail($content,$_POST['email'],$_POST['phone'])==1){
       echo"<small><font color=green>Sent</font></small>";
    }else{
       echo"<small><font color=red>Failed</font></small>";
    }
}