Buy the smallest/appropriate size of bubble lined envelope
If you find it too big, fold it over to the size of a regular envelope
Place appropriate amount of stamps on the top right hand corner. You can add multiple to add up to the amount. Canada Post guidelines 0-30g $0.85 30-50g $1.20 50-100g $1.80
Write the sender information on top left hand corner and the Receivers information in the middle and preferably in a bold font.
DO NOT go inside the postoffice, Drop it in a red box placed OUTSIDE the post office as it has a drawer compared to a slot inside the post office & record a video as proof.