title: html email issue for a tag value
body: <p>I am sending html email to the client via php mail function. while &amp; sign shown in bold creating problems in email replacing ! %20 something like characters within my ids such as below(in bold).</p>
  
  <pre><code>http://test.com/test-page.php?id=abcd**!**1234&amp;cat_id=23
  </code></pre>
  
  <p>Below is my code.
      $to  = 'test@abc.com'; </p>
  
  <pre><code>// subject
  $subject = 'test';
  
  //message
   $message.='&lt;html&gt;&lt;head&gt;&lt;meta charset="UTF-8" /&gt;&lt;/head&gt;&lt;body&gt;&lt;p&gt;&lt;a href="http://test.com/test-page.php?id=abcd1234&amp;cat_id=23" target="_blank"&gt;Wine **&amp;** Dine Offers&lt;/a&gt;&lt;/p&gt;&lt;/body&gt;&lt;/html&gt;';
  
  // To send HTML mail, the Content-type header must be set
  $headers  = 'MIME-Version: 1.0' . "\r\n";
  $headers .= 'Content-type: text/html; charset=UTF-8' . "\r\n";
  
  // Additional headers
  $headers .= 'To: test &lt;test@abc.com&gt;' . "\r\n";
  $headers .= 'From: test user &lt;no-reply@test.com&gt;' . "\r\n";
  
  // Mail it
  mail($to, $subject, $message, $headers); 
  </code></pre>
  
  <p>After sending mail i am getting ! and %20 like characters in email. 
  I also tried &amp; except &amp; in email but no use still ! adding within my email html.</p>