Best Item Duplication Glitch Using Mail | ACNH - Animal Crossing: New Horizons (Switch)

ACNH - Glitch - Duplicated items.png
Yet another glitch is discovered that allows you to duplicate materials such as Gold Nuggets and Star Fragments, and other items like Nook Miles Tickets! Read on for our guide on how to recreate this V1.2.0 glitch found in Animal Crossing: New Horizons (ACNH).

Item Duplication Glitch with Letters

This glitch has been patched in the V 1.2.1 update and does not work anymore.

Users have been sharing duplication glitches for 1x1 and 2x1 items, but recently, Youtube user Do Whatever Games shared a video on how to duplicate almost any item, including rare materials such as Gold Nuggets and Large Star Fragments, and even up to valuable items, such as works of art and Nook Miles Tickets, using the game's mail system.

Basically, any item that can be attached to a letter can be duplicated.

Take note that this is a glitch not intended by the developers and has been fixed with a game update.

A first duplication glitch was discovered back in March, and was immediately patched in the V1.1.1 update.

Previous Item Duplication Glitches

In May 2020, users have discovered and shared different ways on how duplicate 1x1 and 2x1 items inside your home. If you are interested in that, you can check out their separate pages instead.

Other Item Duplication Guides
Item Duplication Glitch partial.png2x1 Item Duplication Glitch 1x1 Item Duplication Glitch partial.png1x1 Item Duplication Glitch

How to Recreate the Mailbox Glitch

3 Players on the Island are Required

You need 3 accounts
To do this, you need 3 players on the island. If you need to, create 2 more profiles and add their characters to the game.

You Need a Separate Controller

A separate controller is required to play in co-op mode (Party Play). If you are using a regular Switch, you can separate the JoyCons to have 2 controllers.

If you are using a Switch Lite, you need another controller like a JoyCon, or a Switch Pro Controller. The Lite's built-in controllers do not work.

Moveable Mailboxes are Recommended

Moveable Mail box from house upgrades
This is not required, but it makes the whole process faster and safer, as you need to beat the autosave timer.

Steps to Mass-Duplicate Any Item

What You Need
  • Items to duplicate
  • 3 players on your island
    (An extra controller is required)
  • 200 Bells for each mail to send
  • Recommended: Moveable mailboxes
  • Steps
    1 Have 3 player accounts on your island.
    Create 2 more profiles if you don't have them.
    2 If you have moveable mailboxes, place them near Resident Services.
    3 Have Player 1 send the mail to Player 2 with the items to be duplicated attached.
    We reccomend sending only 3 to 5 items at a time.
    4 Start Party Play by calling Player 2, and swap leaders.
    5 Have Player 2 enter and exit a building for the mail to load in.
    6 Swap leaders with Player 1 and end co-op session.
    7 Restart Party Play by calling Player 2 and swap leaders.
    8 Have Player 2 open the letters and grab the presents.
    Do not open the presents and drop the items on the ground yet.
    9 Swap leaders with Player 1, and press the - button to pick residents again.
    10 Select Player 3, and end the session when possible.
    11 Repeat steps 7 to 10, the mail should be unopened and you can get the attached presents every time.
    Important Things to Note
    • The game auto-saves at the start of Party Play (co-op), then at every 3 minutes.
    • You can open the presents and drop the items on the ground when Player 2's inventory is full.
    • Make sure that the game saves before you open the mailbox. If not, the mail will be marked as opened and the items will not duplicate anymore.

    1. Have 3 player accounts on your island

    You need 3 player profiles
    If you're playing by yourself, create two more Switch profiles and add them to your island.

    2. Move mailboxes near Resident Services

    Move your Mailbox to the Plaza
    This is not required, but we recommend having moveable mailboxes so you can place them near Resident Services.

    The reason for this is that every time you start co-op mode (Party Play), you will always be taken to the Plaza. This way, you can access the mailbox faster and not risk having the game save at crucial times.

    3. Have Player 1 send the mail to Player 2 with the attached items

    Send a Letter with Items
    Use Player 1 to send letters with the items to be duplicated attached to Player 2. We recommend sending only 2-5 items at a time, to be able to do the glitch successfully.

    4. Call Player 2 to the game and swap leaders

    Call player 2 with Call Resident
    Now, start co-op mode (Party Play) by selecting to call a resident on your NookPhone, and select Player 2.

    You will be redirected to the Plaza to configure the controllers. After that, shake Player 1's controller to swap leaders and press A on Player 2's controller to confirm.

    5. Have Player 2 enter and exit a building for the mail to load in

    Enter a building to load the mail
    You can fast-forward 1 day after sending the mail to have it delivered. Alternatively, you can use Player 2 to enter or exit any building, so that the mail loads into their inbox.

    6. Swap leaders with Player 1 and end the co-op session

    End Session
    Shake Player 3's controller to swap leaders with Player 1. Using Player 1's character, press the - button to end the session.

    7. Restart Party Play by calling Player 2 and swap leaders

    Swap leader again
    Restart co-op mode by calling Player 2 again, and make them the leader. Now, this is where the race against the autosave time starts.

    8. Have Player 2 open the letters and grab the presents

    Open the Letters and take the presents
    Run to your mailbox to open the letters and get the presents. This is why we recommend moving the mailbox near Resident Services, so you can access it right away.

    Do not open the presents and drop the items on the ground yet. You can do this later on when your inventory is full.

    If the game saves after opening the letters, the glitch will not work and you have to restart the whole process. The game saves at the start of the session, and then every 3 minutes. You can set up a timer on your phone if it helps you track the time.

    9. Swap leaders with Player 1, and press the - button to pick residents again

    Call player 3
    Once putting all the presents in your pockets, swap leaders with Player 1 again. Player 1 will press the - button and select Pick residents again among the options.

    10. Select Player 3, and end the session

    Call player 3 and end session
    This time, call Player 3. After doing the controller configuration, there is no need to swap leaders.

    Press the - button and choose to end the session.

    11. Repeat steps 7 to 10 to infinitely open letters

    Keep going till your inventory is full
    Repeat steps 7 to 10, starting from calling Player 2, getting the presents, and ending the co-op session with Player 3.

    The mail should be unopened and you can get the attached presents every time. If not, then you might have done something wrong, and you need to restart the whole process.

    Make sure that the game saves before opening the mailbox. If the game saves after, the glitch will not work.

    Recommended Items to Duplicate

    You can duplicate any item you want including expensive clothing and furniture, but we recommend duplicating items and materials that are difficult to get.

    Reccomended Items to Duplicate
    • DIY Recipes
    • Rare crafting materials: Large Star Fragments, Gold Nuggets
    • Often-used crafting materials: Wood, Stone, Iron Nuggets
    • Seasonal crafting materials: Acorns, Pinecones, Cherry-Blossom Petals, Mushrooms
    • Nook Miles Tickets
    • Fish Bait (No more crafting!)
    • Works of Art (Large or Wall-Mounted)
    • Large Furniture from Gulliver (that cannot be duplicated with the 1x1 or 2x1 item glitch)

    Items You Cannot Duplicate

    You cannot do this glitch on items that cannot be attached to letters. These include:

    Items that Cannot be Attached to Letters
    • Bugs
    • Fish
    • Flowers (The dug up plant, you can send petals)
    • Trees
    • Shrubs/Bushes
    • Rusted Parts

    Frequently-Asked Questions (FAQs)

    How Long is the Auto-Save Timer?

    The game auto-saves every 3 minutes. The game will also save when using features such as sending mail and starting Party Play.

    Why Am I Not Receiving Letters?

    Usually, letters are sent the next day, but you can force mail to be delivered by fast-forwarding one day.

    Alternatively, while using the player's profile, you can enter a building to refresh the mailbox so any sent mail will load in.

    Can I Do This On a Switch Lite?

    As long as you have an extra controller like a JoyCon or a Switch Pro Controller, you can do this glitch. The Switch Lite's built-in controllers do not work.

    If not, then there is no other way to do this as of now, as you need another controller to be able to play co-op (Party Play).

    You Can Do This With a Regular Switch

    Just separate the two JoyCons in your Switch so that you have 2 controllers.

    Can I Do This Glitch With Only One Player?

    You need 3 accounts
    Currently, you cannot do this with only one player. You need 2 extra players on the island to recreate this glitch as it uses the mail system and Party Play.

    Can I Delete the Other Players After?

    You can delete the other players on your island by starting the game using their profile, and pressing the - button to go to the game settings. From there, you can delete that the player from the island.
    How to Add or Delete Players

    Patch Updates

    Patched in the V 1.2.1 Update

    As of May 21, 2020, a new update is available to download via the Internet, which fixes all the glitches found in the V 1.2.0 update of the game.

    How to Update and Update Patch Notes

    Punishment and Repercussions


    “Fixed a serious bug affecting game balance.”
    Source: Nintendo's Patch Notes re: V1.1.1 Update

    Players who did the duplication glitches were not punished for abusing it. All the items and Bells gotten through this glitch remained in their inventories. However, some have noted that they have lost items along the way while recreating this glitch. Only do this at your own risk!

    Related Links

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    Comment

    9 Anonymous10 months

    The first paragraph explains how this was patched so...why do an article for something that doesn't work?

    8 Anonymous11 months

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      • >>[1751]
        I can help u but u posted 3 days ago my friend code is sw-5512-3912-7805 but we got to play together b4 I can mail u check out trading board lots of help there

      • I have oranges, peaches, and pears.

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