Format requirements

Following these requirements helps us properly process your Letter-post item so it gets to its destination on time.


Envelopes must:

  • Be rectangular
  • Be sealed (you must send irregularly shaped cards or postcards in a sealed envelope)
  • Bear the words “AIR MAIL” or “PAR AVION” printed in block lettering on a black or blue label

Transparent plastic envelopes

  • If the plastic can be written on, we must test and approve a sample.
  • If the plastic can’t be written on, the plastic film must have a 20 mm wide white opaque band. The band must be large enough for the mailing address, postage, and service instructions.

Window envelopes

The window must have a transparent cover parallel to the length of the envelope, which must be easily read.


Postcards must:

  • Use the right-hand half of the back for the addressee, service instructions, and postage
  • Bear the words “POSTCARD” or “CARTE POSTALE” printed in block lettering on the address side except on illustrated and picture postcards