By disabling the confirmation emails for a form, the initial confirmation email will not go out to the supporter. However, if it is a recurring donation, subsequent confirmations will be sent as each donation is processed. Is it possible to stop this?
Unfortunately it is not. The confirmations are generated automatically as part of the same process that charges the supporter. You can either:
1) Remove the supporter's email from their record or 2) Mark their record as do not email
Both of these options will affect your ability to communicate with the client via email or enewsletters, however.