title: wp_mail() method not sending email in some cases
body: <p>That is my code for sending email via <code>wp_mail()</code> method</p>
  
  <pre><code>$user_email = $_POST["user_email"];
  $subject = 'Account is ready.';
  $message = "Hello &lt;b&gt;$user_name&lt;/b&gt;,a new account created for you and you need to create a password, &lt;a href'http:example.com/account?email=$user_email'&gt;click here&lt;/a&gt;  to create a password and login.";
  
  $headers[] = 'MIME-Version: 1.0';
  $headers[] = 'Content-type: text/html; charset=iso-8859-1';
  
  $mail = wp_mail($user_email, $subject, $message, $headers);
  if($mail){
      echo 'Sent email to user.';
  }
   else {
      echo 'Oops something went wrong to sending email.';
  }
  </code></pre>
  
  <p>actually that didn't work I mean not sending the email to user, while modify the <code>wp_mail()</code> method like this</p>
  
  <pre><code>$mail = wp_mail($user_email, $subject, $message);
  </code></pre>
  
  <p>that's working, that the mean it never taken more than three parameters, but I need to add <code>$headers</code> for HTML. </p>
  
  <p>What can I do now?</p>
  
  <p>Any advise?</p>
  
  <p>Thanks</p>