Activation email

When a new subscriber registers (ie enters username, email, password), an activation email is immediately sent to them with a request to activate their account. This is very confusing as we want them to proceed with payment and not be distracted by the email or encouraged to acivate an account that has not been paid for.

I cannot find where that email is created or where it is triggered. Can we shut it off. I am presuming that once payment is processed succesfully, their account is automatically enabled/activated and thus no need for the activation email.

Thanks,
Andrew