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There are several indoor letter boxes inCassette Beasts, and players that interact with them will be prompted to enter a code into a keypad at the back. This prompt will undoubtedly pique the interest of many fans, though they may be confused about exactly what they are to input into the letter box’s keypad. This guide is here to alleviate that confusion, and players can find details onCassette Beasts' mailbox codes in what follows.
To begin, it is important to clarify that mailbox codes are not fixed phrases for players to track down withinCassette Beasts. Instead, these codes come directly from the game’s developer, and it is fairly safe to assume that more of them will be released over time. As such, fans ofmonster collecting video gamesare advised to keep an eye on this guide, as it will be updated as new codes become active and old codes go inactive.
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Cassette Beasts: Letter Box Codes (Active)
There are no active mailbox codes as of Aug 02, 2025.
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This list of inactive mailbox codes was last updated on June 18, 2025.
Cassette Beasts: How to Use Letter Box Codes
The first step toward using a letter box code is locating a mailbox, and there is oneinside Harbourtown’s Gramophone Cafe. Once a letter box has been found, fans ofopen-world RPGsshould simply interact with it, select “yes” when prompted, and then enter the active phrase. These actions will ultimately cause a notification, which indicates that there is a package in the box, to appear, and that package will contain the associated reward.
To note, mailbox codes are sure to remind some players ofPokemon’s Mystery Gifts, as the two features have nearly identical functionality. Fans should thus not be too surprised ifCassette Beastsuses the types of reward that can be claimed from Mystery Gifts as a model for its own offerings. Indeed, it is possible that future letter box codes will grant stickers and other items, though perhaps the developer will stick to awarding Bootleg monsters through the in-game mailboxes.
For the uninitiated, Bootlegs are monsters that have different elements than their standard versions, and their moves match their shifted element. Additionally, these monsters are more likely to earn uncommon and rare stickers, which can be quite valuable indeed. While it is certainly possible to encounter Bootleg monsters in the wild, fans ofJRPGsshould not miss out on the opportunity to claim them quickly through mailbox codes.
