(Mail Services User's Manual, Chapter 3, 4b 1-3)

(1) Certified Mail. This service provides a mailing receipt and a record of delivery. A return receipt (PS Form 3811), which provides proof of delivery, can be obtained for an additional fee. Certified mail service is available only for first-class and priority mail. No insurance coverage is provided. A numbered label and completed receipt (PS Form 3811) must be affixed. Labels may be obtained from central mail centers.

(2) Registered Mail. This service provides added protection for valuable mail. Postage insurance may be purchased to cover articles valued up to $25,000. Registered mail is the most secure mail the U.S. Postal Service offers. It incorporates a system of receipts to monitor registered articles from the point of acceptance to delivery.
Return receipts (PS Form 3811) and restricted delivery services are available for additional fees. Added security may delay delivery by 24 to 48 hours. Return receipts (PS Form 3811) are no longer required for classified mail.

(3) The U.S. Postal Service maintains accountable mail records for 2 years. Refer to the DOE Records Retention Schedule for maintaining all required postal and mail records.