If you’re unable to collect your mail on your own, here is a sample template you can use to write a Canada post authorization letter.
I am writing this letter regarding my post arriving on [date]. Due to inevitable conditions, I will not be able to collect my post on the given date and time. Thus, I authorize my [son/wife/etc.], [Name of the person] to collect it on my behalf.
Kindly provide him/her with all the related information and accept [his/her] signature for the collection. I will ask [him/her] to provide you with 2 identity proofs for verification of [his/her] authenticity. For any further clarification and concerns, feel free to contact me at [Phone number].