How to Move Mail Folders from Thunderbird to Outlook

How to Move Mail Folders from Thunderbird to Outlook

In this blog, we will know how to move mail folders from Thunderbird to Outlook while maintaining the folder structure of emails. Two separate solutions are given with pros and cons. So you may choose as per your requirements.

“Hello, I have been using Mozilla Thunderbird for over 3 years now. But due to unavoidable professional reasons, I need to switch to MS Outlook. The problem is my Thunderbird account has a deep folder hierarchy containing about 4-5k emails that I want to keep even after migrating to Outlook. So I would like to have a solution for the same.”

The given query highlights a user problem regarding the conversion of emails from Thunderbird to Outlook. In addition, the users also wants to keep the entire folder structure intact. Since, Outlook supports PST files and Thunderbird uses MBOX to store its data, the best way to perform this migration would be to convert MBOX files to PST format. Users can also follow a workaround and use EML file as a mediator to move mail folders from Thunderbird to Outlook. Read the complete article to know both these methods in detail.

Technical Implications of Thunderbird & Outlook

Before heading for the conversion, a user must know about the data file formats associated with both these email clients. While Windows Outlook uses MSG and PST format for storing emails, Thunderbird has MBOX format for the same. But the one thing that users don’t know is that Mozilla Thunderbird uses SBD format for organizing folders and maintaining sub folder hierarchy. An example will help users understand this in a better way.

Suppose Thunderbird has a mailbox folder (say, ABC) with 20 emails and 2 subfolders (UVW & XYZ) each having 30 emails each. Then Thunderbird will create an MBOX file named ABC storing 20 emails and a separate ABC.sbd folder storing the MBOX files of UVW & XYZ. In fact if XYZ had some emails and another subfolder PQR, then the user will find XYZ.sbd folder (alongside XYZ mbox file) containing PQR mbox file.

To know where Thunderbird stores it’s data, follow the given steps:

  • In Thunderbird, go to the menu bar and select Tools -> Account Settings
  • A new window will open. Here, select Server Settings option (each configured account will have its own server setting)
  • Scroll down to find the mailbox path corresponding to Local Directory.

Users can copy and open this location to find all the MBOX (no extension files) and SBD files(thsoe with .sbd extension).

#1 How to Move Mail Folders from Thunderbird to Outlook Manually

The manual procedure is a good fit for the users who have time on their hand. Bear in mind that since all folders need to be preserved, it will take extra effort from user’s side. The steps to do so are as follows:

Step 1:

  • Run Mozilla Thunderbird on the system
  • Open the first mailbox folder and select all its emails
  • Press Ctrl+S and create a folder having the same name as the opened mailbox folder.
  • Select it as the location to save all the emails.
  • Do this for all the emails in the Thunderbird account.

Note: Users will have to recreate the entire folder hierarchy of Thunderbird on the system storage. Afterward, users will need to follow the given guidelines and save all the emails in the exact folder.

Step 2:

  • Run Microsoft Outlook on the system.
  • Now, create folders in the exact order as they are in your Thunderbird account.
  • Drag and drop the saved files from the system storage folder to the corresponding folder in Outlook.
  • Do this for all the files and folders.

Note: Users must open the empty mailbox folders in Outlook and then drop the saved files onto the middle panel.

#2 Professional Way to Go About Thunderbird to Outlook Migration

In the manual method, the technical boundaries of conversion are overcome by saving the emails as EML mediator files. However, it still does not reflect the core method of converting Thunderbird files into PST format. Since the core data files are not used, this method may result in unfavorable results like losing some email attributes and such. Plus, the sheer process of creating the complex folder hierarchy again and again along with moving emails is both time-consuming and hectic. For these very reasons, using a professional tool is often recommended by users.

SysTools MBOX converter analyzes the entirety of Thunderbird emails and its data structure. Thus allowing users to move mail folders from Thunderbird to Outlook with proper folder hierarchy. It even preserves the attributes of emails, thus preventing any changes in the email messages and its properties. Users can try this solution for a reliable and efficient migration.

Here are the steps to migrate mails from Thunderbird folders to Microsoft Outlook:

  1. Run MBOX Converter and hit the Add File button.
  2. Choose Thunderbird from the list and set the radio button as per requirements:
  • Default Profile option: Select this to auto fetch Thunderbird email accounts (including all the emails, folders, and the hierarchy)
  • Select file/folder: This option enables a user to fetch selected MBOX files. It is recommended to use folder mode for selecting the SBD folder and its contents (selecting SBD folders will preserve folder hierarchy).
  1. Now, preview all the emails, attachments, folder list
  2. Select Export button from the tope of the menu to proceed to the next window.
  3. Here, select the PST file format from the list of export format options given in the software.
  4. Then, choose the folder where you want to save the PST file after conversion on your local disk.
  5. Finally, click on the Export button to start converting Thunderbird data to Outlook PST format.
  6. Wait for the conversion process to complete and then, go to the destination folder to get the converted PST file.

This is how a user can convert all the data from the Thunderbird mail folders and save them in PST format. Thus, allowing him/her to access the file on any Outlook email client.

To import the PST file to your Outlook, do this:

  1. Open Outlook on your system and click on the File menu.
  2. Go to the Open and Export option and click on it.
  3. Now, select the Import/Export option and again click on Import/Export, if prompted.
  4. Next, in the Import window, choose Import from another program or file option.
  5. Then, select Outlook .pst file option to proceed.
  6. Select the account/folder where you want to import the PST file and browse the converted PST file form your system.
  7. CLick Finish.

You now have all your Thunderbird emails in Outlook.

#3 Another Manual Method to Move Thunderbird Folders to Outlook

Step 1: Add a Webmail account in Thunderbird

  1. First, log in to your Webmail account, click on the gear icon and open the Webmail settings.
  2. Select Forwarding and POP / IMAP >> to enable the IMAP option.
  3. Now configure the IMAP account and click on the “Save changes” option
  4. Run Thunderbird, provide your Thunderbird account name, email address and password, and click the “Continue” button to open it.
  5. Click the IMAP checkbox and provide all the necessary information. Then click the Retry button.
  6. Once you have provided all the information correctly, select the option to create a new account.
  7. Finally, open any email to verify the account in Thunderbird.

Step 2: Set up the Webmail account in Outlook

  1. First open the File menu and click Add Account.
  2. Then a dialog box will pop up where you can choose to manually configure server settings or other server types, then click Next.
  3. Then click the Internet Email >> Next button to continue.
  4. Now provide your name, email address and password in the dialog box.
  5. Now select the IMAP option from the account type as IMAP mail account.
  6. Here, enter imap. <servername> .com and smtp. <servername> .com is used in turn for inbound and outbound servers.
  7. Then click on More Settings.
  8. Go to the outgoing server and select my outgoing server (SMTP).
  9. Then, click on the “Use the same settings as my receiving server” option.
  10. Enter the port number 993 under the incoming server port.
  11. So select this server requires an encrypted connection option.
  12. Then enter the port number 587 for the outgoing server, and then click the “OK” button to exit the dialog box.
  13. Click the “Verify Account Settings” option to verify your account settings.
  14. After receiving the message “Your account settings are correct”, click the “Next” button.
  15. Finally done.


To know how to move mail folders from Thunderbird to Outlook, users either need to convert the emails in PST format or use EML as a mediator file. However, with the added complexity that preserving folder structure and email attributes bring, the manual method may not work seamlessly for large migration. In that scenario, users can opt for a professional solution that can easily move all the Thunderbird files to Outlook in a seamless manner.

User Queries

This article adheres to various user queries asked on the internet. Some of these queries are:

  • how to move mail folders from Thunderbird to Outlook
  • how to move folders from Thunderbird to Outlook
  • how to import local folders from Thunderbird to Outlook
  • how to migrate sbd folders from Thunderbird to Outlook
  • and many more…


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