Where do I mail the box mailer?

Canada Post intentionally designed the community hubs outgoing mail receptacles to accept Standard Lettermail, and not Oversize Lettermail. The red metal rain guard is on such an angle that often oversize lettermail won’t fit through.

Not to worry, your box still counts as Oversize lettermail even if you don’t fit this slot. You can deposit the box at your local post office or in the large red street receptacles. 

Know that the “20mm” size requirement is for the processing of mail in the sorting machinery at the CP facilities, not for the receptacles where you drop your mail off.