title: Php mail() is not sending mail to hotmail user but working with all others
body: <p>I am sending mail using <code>php mail()</code> function from my dedicated server through php script. Script is sending mail to all email users except hotmail users. Here's my code for <code>mail()</code> function</p>
  
  <pre><code>$hyperlink = 'http://test.guru99.com/';
  $to ='user@hotmail.com';
  $subject ='Test Mail';
  $message = '&lt;p&gt;For Testing open '. $hyperlink .'&lt;/p&gt;';
  $headers = 'From: user@domain.com';
  $headers .= ' Career Guru99'. "\r\n";
  $headers .= 'Content-type: text/html; charset=iso-8859-1' . "\r\n";
  mail($to, $subject, $message, $headers);
  </code></pre>
  
  <p>This code is working fine for all email users <code>(like gmail, yahoo, hosted domain)</code> but not for hotmail users. My script and code is correct. I think my headers are correct but I couldn't find the cause. I want to send mail with html formatted.</p>
  
  <p>I checked the server logs, the error I ma getting is "Message could not be delivered. Please ensure the message is <strong><em>RFC 5322 compliant"</em></strong></p>
  
  <p>I have checked online and tried to set various headers for the email but did not work</p>
  
  <p>Please give me Suggestions.</p>