When we sign up a customer with Customer Center, an email is sent to the customer. For some reason, our message has no link for the customer to go. Where is the message in Netsuite ?

Setup > Company > Email Preferences > Templates. You can see the list of templates from Setup > Company > System Email Templates

I see. Now here is the problem. The previous developer removed the link for the user to sign up. Can someone tell me the url to go to customer center ? I will add it in the email