How to Back Up Thunderbird Emails?

Updated on January 12th, 2022

Kuljeet Singh

Summary: In this guide, you will learn methods to backup Thunderbird emails and protect your Thunderbird emails from corruption and damage. By following this guide, you can backup Thunderbird emails in various formats, such as PST, EML, MBOX, HTML, RTF, PDF, and Office 365.

Thunderbird is an open-source email client by Mozilla Foundation, which stores all your emails, attachments, filters, contacts, etc. in a separate folder from the installation folder. Similar to Outlook, you can add and configure multiple IMAP or POP email accounts in Mozilla Thunderbird.

However, unlike Outlook, Thunderbird uses MBOX file format to store the mailbox data. MBOX is a mailbox file that is widely supported by many email client apps such as Apple Mail, Eudora, Opera Mail, etc.

As Thunderbird is used for business communications, it contains valuable data that you must back up regularly to protect it from damage or corruption. You may also want to backup Thunderbird emails to migrate them to other MBOX email clients or MS Outlook.

In this guide, we have discussed various methods to back up your Thunderbird mailbox data in different file formats for quick restore in different email clients, including MS Outlook.

Methods to Backup Thunderbird Emails

There are two ways to backup Thunderbird emails,

  • Copy the profile folder that contains all the MBOX files (belong to your email profile in Thunderbird) to an external or network drive
  • Export the Thunderbird mailbox (MBOX) data to different formats, such as PST, EML, PDF, HTML, RTF, and Office 365

Method 1: Backup Thunderbird Emails Manually

To create a backup of Thunderbird emails manually, follow these steps,

  • Navigate to the following location on your PC,
  • Copy the MBOX files and save them to a different volume, external drive, or network storage media for backup

NOTE: You will see .msf files (Mail Summary File), which contain the email header information, and other files without any extension. The files without extension are MBOX files that you need to copy and backup.

  • You can later import the MBOX files to Thunderbird by usingthe ImportExportTools option

Alternatively, you can back up individual emails, by using Thunderbird options, as .EML files. To back up individual mail folder manually, follow these steps,

  • Open Thunderbird and click on any email folder that you want to back up, such as Inbox or another folder
  • Select emails. Use the SHIFT key to select multiple emails or use CTRL+A to select all emails for backup
  • Then right-click and choose Save as
  • Browse a folder location where you want to back up Thunderbird emails and click ‘Select Folder
  • This will save selected emails in a particular folder as .EML files, which you can open and view in any email client app

You cannot back up the Thunderbird emails in other formats, such as PST, Office 365, RTF, PDF, or HTML, by using the manual method. To back up Thunderbird emails in other formats, follow the next method.

Method 2: Backup Thunderbird Emails in Other Formats

You can use Thunderbird Add-on such as ImportExportTools NG or a third-party MBOX to PST converter software, such as Stellar Converter for MBOX to back up Thunderbird emails in other formats, such as HTML, CSV, PDF, and RTF.

NOTE: ImportExportTools NG add-on is no more supported by new Thunderbird versions.

The steps are as follows,

  • In Thunderbird, install the ImportExportTools NG add-on
  • Then right-click your email profile to back up all emails and choose ImportExportTools NG
  • Choose Export all the folders options
  • You may also right-click on an individual folder and choose ImportExportTools NG>Export all messages in the folder
  • Select the desired file format to back up Thunderbird emails

As ImportExportTools NG add-on is no more supported by the latest Thunderbird versions, you can use Stellar Converter for MBOX to export and back up Thunderbird emails more conveniently and faster in various formats. The software also exports and back up Thunderbird emails in Outlook importable PST format and Office 365.

The steps are as follows,

  1. Download, install, and launch Stellar Converter for MBOX software
Select MBOX Window
  • In Select MBOX window, select Thunderbird from the Email Client drop-down list
  • Then click on Select File or Select Identity and choose the profile folder that contains MBOX files The default location is,
  • Click Convert to start the Thunderbird mailbox conversion process
Conversion process initiated
  • After the conversion, all mailbox items appear in a tree format on the left pane. You can click on emails to preview them
  • Select the emails or email folders and click Save Converted File 
  • Select the desired format from Save As window, such as New PST, and click Next  
Save As Window with Different File Format Options
  • Click Browse and choose a destination where you want to save the Thunderbird email backup as a PST file
  • After the Thunderbird mailbox is backed up and saved in the PST file, a Selected Items Converted and Saved Successfully message box will appear. Click OK

Now, you can import the backup PST file into any Outlook or Office 365 account by using the Import/Export wizard.


You must back up Thunderbird emails regularly as they may contain critical information and data. Backup helps restore the emails later if they get corrupt or lost due to events such as hard drive failure or system crash. In this guide, we explained a few methods to back up Thunderbird emails in multiple formats. You can use Stellar Converter for MBOX to back up Thunderbird emails quickly in Outlook importable PST file, HTML, RTF, PDF, and Office 365. It also helps you migrate MBOX mailbox data to Outlook and Office 365 in a few clicks.

Besides Thunderbird, the software supports all other MBOX email clients such as Entourage, Spicebird, Pocomail, Eudora, Apple Mail, Mulberry, SeaMonkey, Claws Mail, Opera Mail, Netscape, Mozilla Mail, Evolution, Mutt, Sylpheed, Cone, & GNU Mail.

About The Author

Ravi Singh

Ravi Singh is a Senior Writer at Stellar®. He is an expert Tech Explainer, IoT enthusiast, and a passionate nerd with over 5 years’ experience in technical writing. He writes about Data Recovery, File Repair, Email Migration, Linux, Windows, Mac, and DIY Tech. Ravi spends most of his weekends working with IoT devices and playing games on the Xbox. He is also a solo traveler who loves hiking and exploring new trails. 

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