Important Information for Sending Mail Return Receipt: Return Receipt can only be used when it’s Certified mail, Insured or Registered. The only time it can be used by itself when it’s a merchandize then the brown form will accompany the green Return Receipt form. Delivery Confirmation: Delivery Confirmation can be used with priority mail or Standard but not First Class. It only tells you when and where a package was delivered. Registered Mail: Registered Mail cannot be sent in bubbled envelopes when it’s domestic, but it can to International country. Express Mail: Express Mail is guarantee 2-day delivery. Postage can be claimed when it’s not delivered within two days.