title: Href link not working in PHP mail
body: <p>I tried to find a solution, but so far, I wasn't able to find anything suitable for my problem.</p>
  
  <p>I want to send a registration mail to every new user I have, this is the PHP for my mail:</p>
  
  <pre><code>&lt;?php
  $message = '&lt;html&gt;
  &lt;body&gt;
  &lt;p&gt;Hi ' . $fname . ',&lt;/br&gt;&lt;/br&gt;
  welcome!&lt;/p&gt;
  &lt;p&gt;
  &lt;a href="\http://www.home.com/en/verification.php?id=' . $db_id . '&amp;code=' . $code . '\"&gt;Please click this link&lt;/a&gt; to activate your account.&lt;/p&gt;
  &lt;p&gt;We hope you enjoy our page and are happy to hear about your experiences!&lt;/p&gt;
  &lt;p&gt;Your team&lt;/p&gt;';
  
  $header  = "MIME-Version: 1.0\r\n";
  $header .= "Content-type: text/html; charset=iso-8859-1\r\n";
  $header .= "From: Sender &lt;sender@sender.com&gt;";
  $header .= "X-Mailer: PHP ". phpversion();
  
  mail($email, 'Thank you for registering!', $message, $header);
  ?&gt;
  </code></pre>
  
  <p>Somehow the link is not working correctly in my mails. In Outlook, my Href appears in brackets (e.g. [<a href="http://www.home.com/en/verification.php?id=4&amp;code=5]" rel="nofollow noreferrer">http://www.home.com/en/verification.php?id=4&amp;code=5]</a>) and in Gmail, only my link description is displayed, but I'm not able to click the link.</p>
  
  <p>Anybody who can help me out?</p>