Quick and Easy Direct Mail Campaigns for Maximum Results

Flat Size Addressing

The post office came up with a new rule in March 2009 for addressing flat size pieces for machine automation. While challenging for mailers, it makes sense for sophisticated postal machines that speeds up mail processing.

Flat size is defined as larger than letter-size (6-1/8x11-1/2x1/4″ with length by height ratio between 1.3 & 2.5) and maximum 15x12x3/4″.

Top-Half Addressing

For Postcard or Envelopes (sealed on 4 sides):

  • Position mail piece vertical (height is the long side)
  • Position the address panel above the middle of the height
  • In that top-half zone, the address can be vertical facing left or facing right, or simply horizontal (just not upside down)
  • In this type of flat piece, there are 4 different top-halves.

For Non-Envelopes or Unenclosed Flat (sealed on 1 side):

  • Position the last fold (or sealed side) on the right side
  • Position the address panel above the middle of the height
  • In that top-half zone, the address can be vertical facing left or facing right, or simply horizontal (just not upside down)
  • In this type of flat piece, there are 2 different top-halves.

For more information in addressing automation compatible flat size pieces, download this document

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