In every Animal Crossing series game, a mailbox can be found outside the player's house. It is used as a place where letters from villagers from the player's town, a villagers from a friend's town, the Town Hall, an item ordered from Tom Nook, the Happy Room Academy, the player's parents, and letters written by the player that have not yet been posted are stored. In Wild World, the player can store their Note-in-a-bottles in the mailbox, which they can buy from Nook's Cranny.
When a letter arrives, a blue flag with a small, white blinking letter will appear on the right-top of the mailbox. Pete arrives in town daily at 9:00AM and 5:00PM in order to make his deliveries. Even though a player can enter another player's house, only the owner of the house can open the mailbox of their home. When time traveling, if the mailbox fills up, all the other letters to that player will be erased. If the player's mailbox, or another player in town's mailbox gets full, Pete will come and tell them that their mailbox is full.
The Mailbox can hold up to 10 letters, similar to the letter space in the player's pocket. When full, the mailbox itself will begin to flicker.
In City Folk, letters can be found in a special part of the player's pockets by clicking a pink icon at the top right of the screen when the player opens up their inventory. In all other versions, the mail is on the right-hand side in the pockets menu, excluding New Leaf where it is located in the top left. Fish and bugs cannot be stored in the mailbox.
In New Leaf, the mailbox can be customized in a number of ways by visiting Nook's Homes, located in Main Street. Whenever there is a full set of mail in the mailbox, it can be shown rattling with the notification blinking rapidly.
In New Horizons, the mailbox has a storage space of 300. It comes in a variety of sizes, color and customization options. The player can move the location of the mailbox after sufficently upgrading their house.