Depending on if you are sending an Advanced or Basic Mass Email your subscription may be different. It's possible that you sent more than your subscription allows because the last mailing pushed you over the limit but eTapestry chose to finish sending all of the emails for you as a courtesy.

Please reach out to sales@eTapestry.com or your account executive at eTapClientAccountExecs@blackbaud.com to ask about purchasing additional emails.