7-6.1 If your manifest mailing includes pieces with extra services, list the pieces on PS Form 3877, Firm Mailing Book for Accountable Mail, or a computer-generated facsimile PS Form 3877. The Postal Service uses the information on PS Form 3877 to respond to claims for loss or damage to mailpieces and to inquire about other services requested. The Postal Service acceptance personnel will sign and date the summary page and return the manifest. This will serve as your record of the pieces mailed.