What is a UPS Delivery Confirmation Adult Signature-Required?

For an additional $5.25 per package, UPS will require a signature by a recipient over 21 years of age. This feature is required when shipping alcohol or other age-restricted content. It also offers peace of mind, knowing that a package will be signed for by the appropriate audience.

In EasyPost, you can set ADULT_SIGNATURE on the delivery_confirmation string to trigger this.