Postal Explorer >
IMM Issue 34 - International Mail Manual >
1 International Mail Services > 140 International Mail Categories > 142 Envelope and Card Specifications
Light–colored envelopes and cards that do not interfere with the reading of the address and postmark must be used. Do not use brilliant colors.
Envelopes and cards must be constructed of paper strong enough to withstand normal handling. Highly glazed paper or paper with an overall design is not satisfactory.
Window envelopes must be used under the following conditions:
Envelopes and cards that have green–colored bars or red– and blue–stripped borders may be used for the sending of First-Class Mail International items.