There were boxes with letters around the map everyday for a limited time. These boxes have a letter on them which will lead them to a code being found. If you know the code before the last letter is released you cannot redeem it.
When you click on the box you will reveal a timer (measured in hours) telling how much time is left until the next box appears.
- Blank (space)
The code has been revealed as "early gift", rewarding a Present. The code has expired since then.