Answering my own question https://www.mentalfloss.com/article/71244/what-are-those-dark-green-mailboxes-dont-accept-mail
Is this correct?
Hello @shermint! You have such a good eye! 
Green boxes are next to many yellow boxes. They are auxiliary boxes for the exclusive use of postmen. They leave the mail bags there. On long routes they can leave part of the mail there…
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Hehe like a locker for the postman
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Hougang 
Can I post this to the IG?
Of course!
When I traveled to Minsk, Belarus, this summer I took these pictures. The second one is on the main post office building.
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Our auxiliary boxes are purple!
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Welcome to my CMB (Community MailBox). These are found in 
See the middle red area? That is the mail slot where I mail YOUR postcards 
If I am receiving a parcel too big for my mailbox, the Canada Post Mail Carrier leaves a KEY inside my personal compartment (I’m number 5) then I look at the key tag to find the letter that matches the parcel compartment down below. Once I’ve removed my big package (with much excitement 
) I close and lock the door, returning the key through the front hole of the compartment box!
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@saintursula what wonderful service you receive by your Mail Carrier in the US! To pick up your outgoing mail when they deliver yours to your home 
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Would love to see a pic of it! Which country is this?
Hong Kong! I’ll try to get a picture of it for you.
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Disney California Adventure mailbox for outgoing mail. There is no special postmark from Disneyland anymore. However, the boxes still operate as employees take the mail deposited and take it to a post office in Anaheim. The mail later gets postmarked by Anaheim Processing and Distribution Center. Anaheim P&DC.
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Postbox from a “rare” country and a slow mail country. Mexico! Postbox from Correos de México. Izamal, Yucatán, México.
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I love to spot old mailboxes in the UK while visiting. These are from the Isle of Man. The one in the crossroads is from Douglas and the one in the wall in small village called Maughold.
Edited to add the name of Maughold.
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this is my mailbox i bought last month. Few days ago, i received a sticker that stuck on the door, the postman left that note and said, sorry i couldn’t find out the aperture of the mailbox, i had to take off the whole lid of mailbox. 
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Brand new Croatian mailbox outside post office where I usually post my mail. I rather hand my mail in the post office for nice cancellation rather than a machine one or no cancellation at all (that sometimes happens if you drop it in the mail box)
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