Communication message sent too earlier before payment processed

I noticed that the communication message set to be sent Day+0 after a payment made is sent before that payment made. When you register, there are 2 phases: the 1st form where you enter your email, username, password and the second page for the payment.

The email is sent when you are done with the first phase. That's not logic. A user can decide to change his mind before making the payment but he considers active user and register in our database. We need the message to be sent after the payment is effectively processed.

Thanks for your support.