self submitting form reloads page?

if (isset($_POST['submit'])) {

extract($_POST);

$subject = "Contact from Firefly website";
$headers = "From: $firstName $lastName <$email>";

$to = $to . "@fireflylightinginnovations.com";

$message = "Email from:" . "\r\n";
$message .= "$firstName $lastName" . "\r\n";
$message .= "$title" . "\r\n";
$message .= "$company" . "\r\n";
$message .= "$phone" . "\r\n";
$message .= "$email" . "\r\n" . "\r\n";
$message .= "Message:" . "\r\n";
$message .= "$mess";

/* mail($to, $subject, $message, $headers); */
echo "$to<br />$headers<br /><br />$message";

echo '<h3>Thank you!</h3> <p>Your message has been sent.  Someone will contact you within 2 business days.</p>';

} else {

echo $_SERVER['PHP_SELF'];

echo "<form action=\"".$_SERVER['PHP_SELF']."?id=6\" method=\"post\">";
echo '
<label>Send message to:</label> <select name="to">
	<option value="">Select a Recipient</option>
	<option value="sales">Sales</option>
	<option value="engineering">Engineering</option>
	<option value="marketing">Marketing</option>
	<option value="service">Customer Service</option>
</select><br />
<br />
<input type="text" name="firstName" size="20" /> <label>First Name</label><br />
<input type="text" name="lastName" size="20" /> <label>Last Name</label><br />
<br />
<input type="text" name="title" size="20" /> <label>Title</label><br />
<input type="text" name="company" size="20" /> <label>Company Name</label><br />
<input type="text" name="phone" size="20" /> <label>Phone Number</label><br />
<input type="text" name="email" size="20" /> <label>Email Address</label><br />
<br />
<textarea name="mess" rows="10" cols="20">Please use this area to type your message.</textarea>

<input type="submit" value="Send Message" name="submit" />

</form>';

}