Mailboxes for your country’s mail service aren’t seen as being distinct, as they tend to be very generic. In the US, most USPS mailboxes these days tend to be at generic and chain businesses, like grocery stores, convenience stores, malls, Walmarts, etc. None of these have Wayspots where I live, and most likely would get rejected. This is what USPS mailboxes in the US look like:
Now, one country that may be an exception is the UK, where mailboxes there have the insignia for whoever was king/queen at the time the mailbox was installed. For example, the insignia for the current monarch, King Charles III, is C III R, and new mailboxes will have this. There were over 75,000 UK mailboxes installed during Queen Elizabeth II’s reign, so those aren’t considered historic enough at this time, as well as generic. Those with Queen Victoria up to King George VI’s insignias are fewer in numbers, and seen as being more historic.
There’s a thread about this, if you’re interested: UK Postboxes Topic