It has come to the Postal Service’s attention that some mailers may not be preparing their First-Class Mail® (FCM) letter trays as efficiently as possible. The guidelines are outlined in DMM 203.4.3 and the following applies:
1. Mailers must use as few trays as possible;
2. Each tray must be filled to capacity before filling the next tray; and
3. This means trays must be filled to the maximum extent possible.
In addition, the Postal Service™ periodically receives inquiries regarding the definition of First-Class Mail “full-trays” for letters. DMM 235.1.4 specifically states that “full” is between 85% and 100% of the letter tray capacity. The Postal Service requests that each tray be filled to capacity throughout the mail preparation cycle so that handling and operational efficiencies may be optimized. This will reduce the number of trays per mailing which means fewer tray handlings.
— Product Classification, Marketing and Sales, 6-23-16
