In Spain, collection boxes (post boxes) are bright yellow. Many of the modern ones are cylindrical, sometimes with the word "Correos" written sideways, bottom to top.
* 75901 * 75902 (postal boxes only) * 75903 (postal boxes only) * 75904 * 74905 (postal boxes only).
Boxing Day is a legal holiday on the first weekday after Christmas. Christmas boxes are given to service workers such as postal workers on that day.
FU
tarjeta postal or carta postal
Cajas
postal
No not all United States Post Offices have postal boxes available for rent. Post office boxes vary in size and price.
Individual mail receptacles can be any color, although most are white or black.Official "letter collection boxes" for the US Postal Service are dark blue, except that Express Mail boxes may have silver tops, red and white stripes, and an eagle logo as well.Letter boxes (postboxes) in the UK and Australia are bright red, with Australia using yellow Express Post boxes. In France and Germany, mailboxes are yellow.(see the related link for a complete list)
The US Postal Service offers free boxes. These are restricted to use through the USPS.
It's "Codigo Postal" and it means Zip Code.
giro postal
As you said postal code, not zip code, I assume you are referring to Mission Bay in Auckland, New Zealand. This area has more than one postal code for private delivery, but post boxes in this area have the postal code 1744.