The email should explain the reason for the lesser value, such as the condition of the device was different than originally stated in the submission, the device received does not qualify for the instant credit promotion that was applied or the activation lock is turned on (e.g., Find my iPhone).
When we receive your device, we ensure it matches the information you provided during the order submission. If the device doesn't match the description or if it wasn't submitted within 90 days, you may receive less than the appraised value indicated during your order submission. Additionally, if you claimed a promotion but the device you sent isn't eligible for the promotion, we'll provide you with the trade-in value for the device, excluding the promotion.