Reason for slowdown in any procedure is a 50-50 affair, i.e. 50% human error and 50% application failure. Thus, it is important to understand the necessities and keep the application updated as per the requirements. When dealing with desktop-based email applications it is necessary to remember that your data is stored on machine. Thus, maintaining it is your responsibility owing to the fact that it’s under your control. Thunderbird is a cross platform application and thus, is the choice of most users for quick desktop emailing. However, email duplication is an issue that spares none and Thunderbird too has fallen bait to it. In order to attain manageability it is necessary to remove duplicate message in Thunderbird. With every message repeating, it is difficult to keep a track of messages and get a hold of the mailbox storage capacity. In the blog below, all these concerns are discussed in detail to help understand consequences of duplicate messages in Thunderbird. Moreover, the possible fixtures to deal with the situation have also been discussed along, in multiple applicable ways.

Common Email Management Issues

Emails are exchanged in bulk especially when a corporate account is involved. Thus, high amount of maintenance is necessitous for such email accounts. Management issues are a common to occur on a daily basis with likewise accounts. Following are some of the most common issues that users face:

  • Storage Capacity: Desktop email clients are safe to use and offer control over your mailbox by generating local data storage. However, the same file also demands maintenance owing to its limited storage capacity.
  • Loss of Messages: Deletion of messages is of two types, one where the item is moved to trash and other where it is permanently erased. A mix of these scenarios could lead to loss of data unknowingly.
  • Email Duplicates: Local email storage comes with a limited storage capacity and duplication of emails worsens the situation. This happens generally due to technical glitches happening during, account configuration, applying rule, etc.

Occurrence of Email Duplication in Thunderbird

Duplication of emails is the most common issue that usually occurs during configuration. Emails repeat when messages that had already existed on the user’s account Inbox are downloaded all over again in the same or different folder. The reason why you need to remove duplicate message in Thunderbird is that the following mistakes might have probably occurred.

NOTE: Mostly duplicates when take place are listed in an unread state within the Inbox. Thus, distinguishing them from the rest of the mails becomes easier.

The occurrence depends on certain conditions:

  • Might happen when downloading emails every time or one time during configuration
  • Could happen during configuration performed through some mail servers and not all
  • During re-installation of Thunderbird email client or restarting an interrupted download

How to Remove Duplicate Message in Thunderbird:

The only procedure of dealing with duplicate messages is to delete them. We get rid of anything that is unnecessary and is bothering. Especially when the workflow is being affected and resulting in monetary losses, it becomes necessary to get rid of whatever is troubling. Thus, discussed below are some of the workarounds that help in cutting down duplicate contents from Thunderbird mailbox(s) without using a third party tool:

  • If the duplicate emails have been received at once, then you can simply sort them together in the order of their receiving. To do so, go to View followed by Sort by and select ‘Order Received’. However, note that this tactic to remove duplicate email messages in Thunderbird is only applicable in the case where all the duplicates were received on the same day and at the same time. Doing this, groups up all messages together letting you take a proper view at all the duplicate entries in your Inbox. Thus, you can manually select and move the replicas to Trash folder and retain the original ones (considering that they are in few countable numbers).
  • Duplicate emails that are received in unread state and are distinguishable from other unread messages can be grouped together by selecting the respective view. You can choose the view option and choose ‘Unread’ as the preferred view type. This will list all unread messages on the preview pane. Select all these messages and proceed by removing duplicate messages in Thunderbird with whole batch in one go.


NOTE: Do cross check by verifying emails that you are deleting the correct set of emails, i.e. remove duplicate messages in Thunderbird only and not original copies.

  • You can also go for an extension or a plugin in case the above-suggested methods seem to be a lot cumbersome for you. There are many Thunderbird remove duplicate messages add on available from external sources that are the official third party providers of Mozilla Thunderbird. However, do remember they are third party and not Mozilla’s own.

Varied Conditions

In case of varied conditions like a corrupted folder or other miscellaneous possibility, refer the section below for quick tips:

Folder Corruption: Fixing the situation of a corrupted folder is only possible by replacing the items from the affected folder to a new child folder. You need to erase all duplicate messages from the corrupt folder to a newly created folder and exit Thunderbird to delete the affect folder’s MBOX and MSF files from their respective store location. Now, on restarting Thunderbird, the respective folder will be recreated being a default.

TIP: Although it is possible to move back the relocated messages in the recreated folder, it is suggested that users do not do it.

Automated Way to Remove Duplicate Emails Thunderbird

When all else fails we turn to commercial solutions and unload our burden on them. Thus, in the case of email duplication in Thunderbird also we approach third party tools as the last resort to tackle the situation.

Benefits of Third Party: When choosing third party software, you get the luxury of not doing anything – everything is based on commands. There are various options handling the procedure to remove duplicate messages in Thunderbird carefully and others supporting it. Moreover, a freeware trial is provided way before licensed investment for quality and functionality assurance.

Remove Duplicate Message in Thunderbird Like Never Before

Flexibility gives you better results, than staying rigid does. If you are flexible enough to change your client from Thunderbird to one that comes with greater potential, then there is a possibility to remove duplicates successfully. You can convert MBOX file to PST file, which is the proprietary storage format of Microsoft Outlook (greater in potential) and then use Outlook PST duplicate remover to get rid of the redundant files.

This method should be preferred for the very fact that, the duplicates remover for PST comes with a variety of options. The software ensures that you remove duplicates and not lose them in the process too. You can remove Thunderbird duplicates and save them to another folder, which saves you from the necessity of removing duplicates in order to get rid of them. Thus, the software serves convenience at its best than any other discussed solution does.


It is better to be safe than sorry.You must ensure on a prior note that a situation where Thunderbird sends duplicate emails is totally avoided. The headache of removing the duplicates can then be avoided. However, if you do get yourself caught up in a similar situation, don’t forget to avoid going for manual processes and choosing third party tools instead. However, if you do want to experiment with your precious emails and want to know how to remove duplicate messages in Thunderbird on your own then go ahead with the manual approaches. They come with a great scope of losing a great load of messages at once.

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