I've read the docs and I see that the registration email is sent out when a client is created with an email address.
However, since I can make that email also include login information, then it seems to me that email isn't sent out as soon as the first basic customer page is filled out, but sometime after the login information is filled out.
I'm thinking of using the remoting framework to auto-create ISPConfig accounts that match up with Drupal accounts. However, I don't want the user to know that their ISPConfig account has been created until my payment gateway has verified their payment (lots of scammers out there). Ideally, I;d like a big button that says "Send introductory email", but I guess I'm not going to get that
Instead, I was wondering what the exact criteria is that triggers the sending of the introductory email. If I knew that - exactly - then I can build my registration system around it and ensure it doesn't get sent until I'm ready to send it.