allow recursion on dns server?

Hello everyone. I'm not sure if I should allow recursion on our external DNS server. I just finished configuring the server and this is the last parameter I'm pondering over. We are an internet company and we rely on customers going to our website and our website is referred to on our external DNS. I would like to know how recursion will affect our customers and our internal network.

Please advise and elaborate.

See this CERT DNS recursion pdf file