TiL: Canadian Postal Trivia Edition

Things I've learned: even though we've been "All up" -- everything gets sent by air mail -- for longer than I've been alive, Canada's International Letter-post Items Regulations still mandate that all letters and postcards posted in Canada for delivery outside Canada bear the words AIR MAIL and PAR AVION. (Handwritten in bold capital letters in blue or black, or by affixing an Airmail etiquette, to be specific.)