Ok, this was originally two commissions by Silfoe (https://www.deviantart.com/silfoe), the cutie mark first, followed by the main pic (show it some love over here: https://www.deviantart.com/silfoe/a.....ry-804018389).

There's a lot going on in this pic, so lets start with the cutie mark. The cards mean play the hand you're dealt, he spent nearly fifteen years wandering Equestria looking for his place, taking whatever odd job came his way. The compass is somewhat obvious, it refers to his navigational skills, essential for a member of the Harness Guild (freight hauling guild of Equestria). The middle card is a sun, referring to his omnipresent smile and upbeat attitude. Finally the last card refers to another important skill for any delivery pony, time management, deliveries are on time, every time.

As to him, this is the closest to perfect picture I've gotten of him. He does seem to lack some of the bulk you would expect from a half Clydesdale, but everything from colours to horn length to cutie mark is perfect. As to the Amazon boxes, at the time I was working as an Amazon Flex driver, so this seemed appropriate. And he's not just a delivery pony, but the head of the Appleloosa chapter of the guild.