why is $header undefined here? : <p>i am trying to send mail using php. i have removed the comment from the SMTP port and mail but Apache throws undefined variable $header in line no.5. what is wrong here?  </p>

<pre><code>&lt;?php include "head.php";?&gt;
&lt;?php
$from= "smechailes@gmail.com";
$Headers = "";
$header .= "MIME-Version: 1.0 \r\n";
$header .= "Content-type: text/html; Charset= iso-859-1 \r\n";
$header .= "From: ".$from." \r\n";
$to = "setok321@gmail.com";
$subject = "test-mail";
$message ="&lt;h1&gt;hello&lt;/h1&gt;";
$mail = mail($to, $subject, $message, $header);
echo (int)$mail;
?&gt;
&lt;?php include "foot.php";?&gt;
</code></pre>
