My first guess just based on the color and shine of the dog is that it is either the phone booth or a postal box in the UK Pavillon.
Alas, your thoughts are very keen, yet my dog is not from the UK, but he does spend time chasing mail carriers.
Okay, so then I am on the right track that it is a postal box? Now it's a matter of where the box is. I'm going to move to another park with my next guess. But please tell me if I was in the correct park to begin with... Seeing as how this is an extreme closeup, it makes me think that this is out in the public and not in an exhibit. Maybe at DHS on the Streets of America?
You are correct in leaving the park you were in, yet you traveled to the wrong park. I am "temporarily" getting lost in the mail trying to find my dog!
Okay... So we rule out DHS and Epcot. And since you said temporary, my guess is that it is a Christmas decoration. So now it's just figure if it's at DAK or MK, with the more obvious choice being MK. Is there a temporary Christmas Card Mailbox at either Town Hall/Guest Services or by Santa Goofy (courtyard next to Guest Services)?
You nailed it!! It was next to the chair that photos are taken just to the left of Guest Services. Well done Jeff!
Well, your "temporary" clue dialed it in somewhat. From there it was just casting a wide enough net to hit the target.
Finally found a photo of it online (not my pic), but they must have different images on each side of the letter box.