Sometimes we encounter Firewall - Access denied for the Web site you requested, message while surfing from a corporate network. Unfortunately, firewalls sometimes rate a good valid site as blacklisted site. In that case we use to request our system administrator to whitelist that site.
Request Access comes in handy for this purpose. Once you encounter this message, you have to just click Request Access menu in Tools menu of Firefox. Now your mail requesting administrator to unblock the site is ready in your default mail client. Just click send. Your System Administrator's e-mail-id and your full name are configurable through Options button in extensions dialog.