Set cookie i form mail script

Hej.

I følgende form mail script kunne jeg godt tænke mig at man kunne sætte en cookie, så brugere kun kan sende mails, f.eks. hvert 5. minut, men hvordan gøres det?

Mvh.

formmail.php:

<?php
// Your e-mail adress:
$mailto = "name@domain.tld";

# Maximum size of attachment in bytes:
$max_attach_size = 500000;

?><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html>
<head>
<title>Formmailer</title>
<meta http-equiv="content-type" content="text/html; charset=iso-8859-1" />
<style type="text/css">
<!--
body                { font-family: Verdana, Arial, Helvetica, sans-serif; font-size: 13px; color: #000000; background: #ffff3; margin: 20px; padding: 0px; border: 0px; }
.caution            { color: red; font-weight: bold; }
-->
</style>
</head>
<body><?php
/*if (empty($_POST['form_submitted']))
{
  ?><p>Please fill out the form:</p><?php
}
*/
if (isset($_POST["form_submitted"]))
{
  $name = $_POST['name'];
  $email = $_POST['email'];
  $subject = $_POST['subject'];
  $text = $_POST['text'];

  unset($errors);
  if ($email != "" and !preg_match("/^[^@]+@.+\.\D{2,5}$/", $email)) $errors[] = "e-mail address seems to be invalod";
  if ($text == "") $errors[] = "no message entered";
  if ($_FILES['probe']['size'] > $max_attach_size) $errors[] = "attachment too large (".number_format($_FILES['probe']['size']/1000,0,",","")." KB) - maximum size: ".number_format($max_attach_size/1000,0,",","")." KB";

  if (empty($errors))
  {
    $text = stripslashes($text);
    $subject = stripslashes($subject);
    if ($name != "") $mail_name=$name; else $mail_name="Unknown";
    if ($subject != "") $mail_subject = $subject; else $mail_subject = "No subject";
    if ($email != "") $mail_email = $email; else $mail_email = "email@unknown.xyz";
    $ip = $_SERVER["REMOTE_ADDR"];

    // if attachment, MIME-Mail:
    if (isset($_FILES['probe']['name']) && trim($_FILES['probe']['name']) != "")
    {
      // read and encode file:
      $datei_content = fread(fopen($_FILES['probe']['tmp_name'],"r"),filesize($_FILES['probe']['tmp_name']));
      $datei_content = chunk_split(base64_encode($datei_content),76,"\n");
      // Boundary:
      $boundary = md5(uniqid(rand()));
      // Mail-Header:
      $mail_header = "From: ".$mail_name." <".$mail_email.">\n";
      $mail_header .= "X-Sender-IP: ".$ip."\n";
      $mail_header .= "MIME-Version: 1.0\n";
      $mail_header .= "Content-Type: multipart/mixed; boundary=\"".$boundary."\"\n";
      $mail_header .= "This is a multi-part message in MIME format.\n";
      // Mail-Text:
      $mail_header .= "--".$boundary;
      $mail_header .= "\nContent-Type: text/plain";
      $mail_header .= "\nContent-Transfer-Encoding: 8bit";
      $mail_header .= "\n\n".$text;
      // Attachment:
      $mail_header .= "\n--".$boundary;
      $mail_header .= "\nContent-Type: ".$_FILES['probe']['type']."; name=\"".$_FILES['probe']['name']."\"";
      $mail_header .= "\nContent-Transfer-Encoding: base64";
      $mail_header .= "\nContent-Disposition: attachment; filename=\"".$_FILES['probe']['name']."\"";
      $mail_header .= "\n\n".$datei_content;
      // End:
      $mail_header .= "\n--".$boundary."--";
      // Send E-mail
      if (@mail($mailto,$mail_subject,"",$mail_header)) $sent = true; else $errors[] = "no connection to the mailserver - please try again later";
    }
    // no attachment, normal E-mail:
    else
    {
      $mail_header = "From: ".$mail_name." <".$mail_email.">\n";
      $mail_header .= "X-Sender-IP: $ip\n";
      $mail_header .= "Content-Type: text/plain";
      if (@mail($mailto,$mail_subject,$text,$mail_header)) $sent = true; else $errors[] = "no connection to the mailserver - please try again later";
    }

    // copy to sender:
    if (isset($sent) && isset($email) && $email != "" && isset($_POST['copy']))
    {
      if (isset($_FILES['probe']['name']) && trim($_FILES['probe']['name']) != "") $copy_mail_text = "Copy of the e-mail:\n\n".$text."\n\nAttachment: ".$_FILES['probe']['name']; else $copy_mail_text = "Copy of the e-mail:\n\n".$text;
      $header= "From: ".$mailto."\n";
      $header .= "X-Sender-IP: ".$ip."\n";
      $header .= "Content-Type: text/plain";
      @mail($email, $mail_subject, $copy_mail_text, $header);
    }
  }
}

if (empty($sent))
{
  if(isset($errors))
  {
    ?><p class="caution">Error:</p><ul><?php foreach($errors as $f) { ?><li><?php echo $f; ?></li><?php } ?></ul><br /><?php
  }

  ?><form method="post" action="<?php echo basename($_SERVER["PHP_SELF"]); ?>" enctype="multipart/form-data"><div>
  <p><b>Name:</b><br /><input type="text" name="name" value="<?php if (isset($name)) echo htmlentities(stripslashes($name)); else echo ""; ?>" size="35" /></p>
  <p><b>E-mail:</b><br /><input type="text" name="email" value="<?php if (isset($email)) echo htmlentities(stripslashes($email)); else echo ""; ?>" size="35" /></p>
  <p><b>Subject:</b><br /><input type="text" name="subject" value="<?php if (isset($subject)) echo htmlentities(stripslashes($subject)); else echo ""; ?>" size="35" /></p>
  <p><b>Message:</b><br /><textarea name="text" cols="55" rows="12"><?php if (isset($text)) echo htmlentities(stripslashes($text)); else echo ""; ?></textarea></p>
  <b>Attachment:</b><br /><input type="file" name="probe" value="<?php if (isset($_POST['probe'])) echo htmlentities(stripslashes($_POST['probe'])); else echo ""; ?>" size="20"/></p>
  <br /><br />
  <p><input type="submit" name="form_submitted" value="OK - Submit" /> <input type="checkbox" name="copy" value="true" /> Copy to sender</p>
  </div></form><?php
}
else
{
  if (empty($email)) { ?><p><b>Thank you!</b><br />The message has been sent successfully but you didn't specify your e-mail address so I can't reply.</p><?php }
  else { ?><p><b>Thank you!</b><br />The message has been sent successfully.</p><?php }
}

?>
</body>
</html>