The grey boxes are relay boxes which mostly exists downtown. They work for foot routes. So the letter carrier at the start of the day organizes their route and place mail in specific bags and tag them. Then someone else will drop the mail at specific points. The letter carrier then starts at one point and deliver mails and by the time they get to the next point they will have finished mail for that relay point. They will then open up the relay box to get mail for their next leg of their route.

How parcel delivery work is if there is need of a signature or we can't safe drop it we will give you a delivery notice card put it in your mail box and then we take the parcel back in the depot. We put the parcel in a cart and the next morning another carrier will bring the parcel to a retail postal outlet like SDM.

Usually an address will only have one letter carrier but this time of year you might have more because of volume. The normal letter carrier won't be able to fit everything in their vehicle. My supervisor had me and 2 other guys service 2 condos with about 400 occupants each. My vehicle was filled just with my normal deliveries without those two condos. So that's why you might see more than one guy this time of year.

SDM are SDM employees. Not CPC employees. So training is handled by SDM.