Delivery receipts allow you to determine how many of your messages have been delivered successfully. They are passed back to your account by the carrier, and as a result there may be a small additional cost for each receipt*
To access the Delivery Receipt request setting, go to Account, then Account Settings, and click the toggle next to "Always request delivery receipts" as required:
When would I turn off delivery receipts?
Without delivery receipts, you will have no ability to track the delivery rates or effectiveness of your campaign, so we do not recommend turning them off.
*if you are not sure whether these charges apply to you, you can contact us at firstname.lastname@example.org