Postal codes are widely used in shipping industry, it is important information for the delivery man to locate the accurate address and make it convenient to dispatch. Plastic seals are widely used in shipping and postal industry. A Canadian postal code is a six-character string that forms part of a postal address in Canada. Like British and Dutch postcodes, Canada's postal codes are alphanumeric. They are in the format A0A 0A0, where A is a letter and 0 is a digit, with a space separating the third and fourth characters. According to Statistics Canada, about 850,000 postal codes exist in Canada, using Forward Sortation Areas from A0A in Newfoundland to Y1A in Yukon.

Canada Post provides a free postal code look-up tool on its website, via its applications for such smart phones as plastic seals and BlackBerry, and sells hard-copy directories and CD-ROMs. Many vendors also sell validation tools, which allow customers to properly match addresses and postal codes. Hard-copy directories can also be consulted in all post offices, and some libraries. The amount of mail sent to Santa Claus increased every Christmas, up to the point that Canada Post decided to start an official Santa Claus letter-response program.

Numbered postal zones were first used in Toronto and arrived in other Canadian cities by the 1940s. Mail to a Toronto address in zone 5 would be addressed in this format. Afterwards, the Post Office began implementing a 3-digit zone number scheme in major cities to replace existing 1- and 2-digit plastic seals. Besides Toronto, the system was to have expanded to London, Ottawa, Quebec City, and Vancouver. With impending plans for a national postal code system, Postmaster General Eric Kierans announced that the Post Office would begin cancelling the new 3-digit city zone system. Companies changed their mail addressing at their own expense only to find the new zoning would prove to be short-lived.