Create invoice when registrating I have a register form with some fields like name shop, btw number, subscription, ... . I want to create an invoice of the data filled in (do some operations with other variables). I know that there's a drupal module Invoice but how can I automatically create one when clicked on register button and send them to the users email? (I'm a drupal beginner)
I can't tell you the exact steps but I can suggest you some workaround for this.

You can use Rules module &amp; create a rule for sending mail after event register.

You can send mail in action. Use Token for mail formatting. Maybe you will need some Mail related modules such as Mime Mail for sending mail.