The final cost of a Preorder Alert is based on total eligible followers and is determined 30 days in advance of the alert’s mailing date. However, all eligible followers as of the mailing date will receive the Preorder Alert email. Eligible followers include any followers in the US who are subscribed to receive these alerts from authors they follow.
You’ll see an estimated eligible follower count when you schedule an alert, but please note that this number may change by the alert’s mailing date. You can learn more about eligible follower counts here.