Okay I am sending an activation email link to user's email. My Activation link is working perfect I wants to make that link expire after X minutes.
Here is my code:

```
$base_url='http://172.16.0.60/WebServices/';
$activation=md5($email.time());
email format to HTML
        $mail->Subject = 'Activate Your Account';
        $mail->Body    = 'Hi, <br/> <br/> We need to make sure you are human. Please verify your email and get started using your Website account. <br/> <br/> <a href="'.$base_url.'activation/'.$activation.'">'.$base_url.'activation/'.$activation.'</a>';

```

Now my
 .htaccess file

```
 RewriteEngine On

    RewriteRule ^activation/([a-zA-Z0-9_-]+)$ activation.php?code=$1
    RewriteRule ^activation/([a-zA-Z0-9_-]+)/$ activation.php?code=$1

```

Now how can I make my link expire? I dont have timestamp field in my database.