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How to Migrate Apple Mail to Thunderbird Without Data Loss?

  Rollins Duke
Rollins Duke   
Published: March 2nd, 2026 • 7 Min Read

Apple Mail to Thunderbird migration involves exporting Mac Mail emails (in MBOX/EML format or from Apple Mail) into the Thunderbird profile folder on Mac or Windows while preserving attachments, folder structure, and all other email attributes.

There are multiple ways to migrate Apple Mail to Thunderbird:

  • Free-native import option in Thunderbird for Mac
  • Using ImportExportNG Tool
  • Using an IMAP account as a bridge for non-technical users.
  • Professional Apple Mail to Thunderbird Converter – for bulk data handling & to import backed up Mac Mail emails in Thunderbird.

Why Export Apple Mail to Mozilla Thunderbird?

There may be a few reasons why you want to migrate Apple Mail to Thunderbird:

  • Migrating Apple Mail to a Windows/Linux-based computer, as Thunderbird is an email client compatible with all OS for free.
  • Thunderbird offers better third-party integration and filters as compared to Mac Mail.
  • Add-ons in Thunderbird offer multiple advanced functionalities to users that are not natively possible in Mail for Mac OS.
  • To access Apple Mail backup files in Thunderbird for easy viewing and access.

Method 1: Migrate Apple Mail to Thunderbird Using Free Native Tool

Mozilla Thunderbird has a free native option to import Apple Mail emails directly while preserving complete data integrity.

Pros Cons
It is the free & secure approach as it keeps data local. Limited if you want to switch email clients on Mac OS.
Migrate Mac Mail to Thunderbird with “On My Mac Folders” Newer versions, like Supernova/Nebula 115 and 128 series, may not have this option.

Important: Always download Thunderbird from the official source.

  1. Launch the Thunderbird Application after downloading.
  2. Click on Menu (Three-line on top right). Select Tools.
  3. Select Import and then Import from Apple Mail.
  4. Choose the Import from Profile option.
  5. Check the boxes for all the data that you want to transfer from Apple Mail to Thunderbird.
  6. Click on Start Import.
  7. Make sure that after the process is completed, restart Thunderbird and verify if all the emails are properly imported.

Method 2: Export Mac Mail to Thunderbird Using ImportExportNG Tools

Apple Mail/ Mac Mail or Mail App for Mac enables you to bulk export emails in MBOX/EML format. You can import these MBOX files into Thunderbird for Mac or Windows using ImportExportNG tools.

Pros Cons
This method works for backed-up Apple Mail email migration to Thunderbird (EML or MBOX). Limited to Mailboxes smaller than 4GB.
Suitable for cross-device Apple Mail to Thunderbird migration. Emails may lose folder structure and can get corrupted.
No dependence on the internet to transfer Apple Mail to Thunderbird. Requires technical skills.

Phase 1: Export Apple Mail email in MBOX Format

MBOX format is more suitable to migrate Apple Mail to Thunderbird as it can store multiple email messages in a single file.

  1. Open Mac Mail.
  2. Select the Apple Mail Mailboxes to be transferred to Thunderbird.
  3. From the Mailbox tab, select the Export Mailbox option.
  4. Choose the saving location and name the file.
  5. Repeat the process for all the Apple Mail folders.

If you are exporting Apple Mail emails to Thunderbird on another device, use a USB/Flash drive or cloud storage to transfer emails to the destination computer.

Phase 2: Import Apple Mail Emails in Thunderbird

  1. Once you have installed and set up Mozilla Thunderbird on your system, go to Menu >> Add-Ons and install the ImportExportNG Tools add-on.
  2. Scroll to Local Folders on the Mail panel on the left bar of Thunderbird.
  3. Right-click and create a New Folder; you can name the folder as Apple Mail Import.
  4. Right-click on the folder once created & select ImportExportNG Tools.
  5. Select Import MBOX Files >> All MBOX from Directory with SBD for folder structure preservation.
  6. Select the Apple Mail MBOX folder & press Open.

How to Import Mac Mail (EML) in Thunderbird?

Mac Mail can export emails in EML format using a simple drag & drop in Mac. If you have saved Apple Mail emails in EML in case you have limited emails or an older backup available, you can follow the steps below to migrate Apple Mail to Thunderbird:

  1. Ensure to install ImportExportNG Tools in Thunderbird.
  2. Go to the Local Folder.
  3. Right-click and select New Folder to make a dedicated folder for Apple Mail import in Thunderbird.
  4. Again, right-click on the newly created folder, choose ImportExportNG Tools.
  5. Select Import EML messages >> All EML from a directory.
  6. Select the EML files and wait for the process to get completed.

Method 3: Migrate Apple Mail to Thunderbird Using IMAP Bridge

If you are transferring Apple Mail to Thunderbird on another device and find the ImportExportNG method complex due to technicalities. Using an IMAP email account bridge is a simpler approach.

  1. Open Mac Mail and choose Mail >> Add Account.
  2. Enter your email address (any mail account, iCloud, Gmail, Yahoo, with a sufficient storage quota will be functional).
  3. Follow the instructions to configure a new account.
  4. Drag and drop the folder(inbox, sent, draft, or On My Mac folder) to the new IMAP account configured in Apple Mail.
  5. Wait until IMAP sync is completed.
  6. Open Thunderbird Application, right-click on the Navigation Menu, and choose New Account.
  7. Enter the same IMAP email address you configured in Apple Mail.
  8. Follow the pop-up instructions and restart Thunderbird to migrate Apple Mail to Thunderbird.

Apple Mail to Thunderbird Converter to Export Mac Mail Emails in Thunderbird

BitRecover Apple Mail Converter is a secure & easy-to-use desktop-based application for Max & Windows to bulk import Apple Mail to Thunderbird directly. An offline & secure way to migrate Apple Mail to Thunderbird.

Using the automated tool preserves the internal folder structure, email attributes, images, hyperlinks, and metadata, and implements the Apple Mail to Thunderbird migration without email client.

Download the tool for free to export 25 Apple Mail emails per folder to Thunderbird with the demo version.

Compatible with all Apple Mail email files(MBOX, MBX, EML) and Thunderbird versions on standard Mac & Windows OS.

Quick Steps to Migrate Apple Mail to Thunderbird Using Pro-Tool

  1. After downloading, launch the BitRecover Mac Mail to Thunderbird Converter.
  2. Select the files or folder with the Apple Mail email.
    select apple mail files or folder to be imported into Thunderbird
  3. Choose the email folder to be migrated from Apple Mail to Thunderbird.
  4. Choose Thunderbird from the saving option and press Convert.
    Migrate Apple Mail to Thunderbird

FAQs: Apple Mail to Thunderbird Migration

Q1: Will attachments be preserved during the Mac Mail to Thunderbird import?

Yes, with both manual and professional approaches, attachments will be preserved.

Q2: How long does the Apple Mail to Thunderbird migration take?

The downtime depends on the Mailbox size and the number of mailboxes. However, you can significantly reduce the import downtime with Apple Mail to Thunderbird Converter, as it speeds up import with advanced algorithms.

Q3: Will I have to reconfigure my email accounts after migration?

Yes, although the emails can be transferred from Apple Mail to Thunderbird. Passwords and server settings are not thus you will need to re-add each account in Thunderbird.

Ensure to choose the right method for migrating from Apple Mail to Mozilla Thunderbird based on your mailbox size and migration scenario. Always verify the emails before deleting the backup.

And if you need any help importing Apple Mail to Thunderbird. Get in touch with a BitRecover expert anytime, anywhere in the globe, through the Live Chat option for a seamless and integrity-focused migration.


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