Sep 3, 2022 | Email Conversion

Best Way to Remove Duplicate Emails from Thunderbird

By Deepak Singh Bisht

Thunderbird is a free email application developed by Mozilla. Many small businesses and individual users use it as a default email client for sending and receiving emails. However, it sometimes copies duplicate emails, due to which the size of the mailbox increases. The large mailbox size makes Thunderbird slow, due to which the user gets a lot of problems.

In this post, we will discuss the reasons behind the duplicate emails in Thunderbird. We will also learn the simple way to delete duplicate emails from Thunderbird. If you are a thunderbird user and facing the same issue, then this post will be helpful for you.

Why do I get duplicate emails in Thunderbird?

Many Thunderbird users face this problem. In most cases, this happens when you receive new emails from the mail server and get disconnected during that process. When you get reconnected, the email client re-downloads the already existing email from the server. Because of this, you see duplicate emails in your mailbox.

Reasons behind the duplicate emails in Thunderbird

There are many reasons behind receiving duplicate emails. Some of them are mentioned below:

Accidental activities by users: If you have more than one subfolder in your Thunderbird and you are copying a mail to any other subfolder, this can cause duplication.

Issues from the sender side: In case the sender is sending the same email over and over or his internet connection is unstable, then Thunderbird saves all emails. Due to which you may see duplicate emails.

Server issue: The server is important for any email client. But sometimes, there is a problem with the server. Due to which the behavior of the server becomes irrelevant. Due to which it sends the same email to the email client again and again.

How to remove duplicate emails from Thunderbird?

You can use a manual method or third-party Thunderbird Duplicate remover tool to remove duplicate emails from Thunderbird. Here we will use both manual and third-party tools to remove duplicate emails.

Instant Solution - SysCurve MBOX Duplicate Remover Tool

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Quickly Remove duplicates emails from Thunderbird and MBOX files.

Remove Thunderbird duplicate emails using manual method

Here, we are going to use the Remove Duplicate Messages add-on. With the help of this add-on, you can delete duplicate messages from Thunderbird. To perform this task, follow the steps below.

  1. Launch Mozilla Thunderbird.
  2. Go to the Tools tab and select Add-ons.
  3. Search Remove duplicate messages and click on the Add to Thunderbird button.
  4. Thunderbird will show a message Add Remove Duplicate Messages?, click on the Add button.
  5. Once the installation gets complete, restart the Thunderbird.
  6. To check the add-on activation, go to the Tools tab and select the Add-ons option.
  7. Go back to the main account and select the mail folder.
  8. Right-click on the selected folder and select the remove duplicates option.
  9. If you don't have any duplicates, a popup message will inform you. If you have duplicate messages, a screen will show you information about them.
  10. Select duplicate messages, which you want to delete.
  11. Click on the delete selected button.

With the help of this method, you can remove Thunderbird duplicate emails. However, the manual solution is long and requires technical expertise. If you are searching for a simple way to perform this task, try SysCurve Thunderbird duplicate remover tool.

Remove Duplicate Messages from Thunderbird using MBOX Duplicate Remover Tool

Here we are going to use the SysCurve MBOX Duplicate Remover Tool. Using this tool, you can quickly Thunderbird duplicate emails. The software also allows users to remove duplicate emails from MBOX and MBX files. To perform this method, follow the steps below.

  1. Download and install the SysCurve MBOX Duplicate Remover tool
  2. Open the tool and select the Load Default Thunderbird Directory option
  3. Select Match Filter as per your requirement
  4. Click the Browse button and provide a location to save the new file
  5. Click the Remove Duplicate Emails
  6. After that, the software will remove all duplicate emails and save a file on your selected location.


In this post, we discussed the reasons behind the duplicate messages and how to delete duplicate emails from Thunderbird. We also learn how to remove Thunderbird duplicate messages using SysCurve MBOX Duplicate Remover tool.

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