Take your mail with you: from Outlook and Apple Mail to Thunderbird

Thunderbird 128.x and newer has a built-in import wizard that takes over email, accounts, and settings from other clients — but only under strict conditions. This article explains what those conditions are and how you move your messages, folders, and settings to Linux.

Requirements

• Thunderbird 128 or newer, installed on the source system (Windows or macOS)
• The source application (Outlook or Apple Mail) active and installed on that system
• Your email account that you want to transfer
• For IMAP accounts: your login credentials and server settings

The import wizard only works on the system where the source application is located. That means: if you want to go from Windows to Linux, run the import on Windows and then copy your Thunderbird profile.

Why the source application must be present

The biggest misconception during migration: a .pst file from Outlook is not enough. Thunderbird does not read those files directly. The import wizard uses Outlook's own API to read the content — and that API only exists if Outlook itself is installed. Without Outlook, no import. That also applies to Apple Mail: the wizard reads the local Mail.app database, which only exists on macOS.

This means you cannot jump from Windows or macOS to Linux in one step. You always need an intermediate step on the old system.

Step 1: Import into Thunderbird on Windows or macOS

Install Thunderbird on your current system and start the import wizard:

1. Open Thunderbird

2. Go to Menu (☰) → Tools → Import

3. Choose Email and select the source application

For Apple Mail (macOS): choose "Apple Mail" as the source. The wizard scans the local Mail.app storage and copies mailboxes, folders, and messages.

For Outlook (Windows): make sure Outlook has been opened at least once and your account is active. Choose "Outlook" as the source. The wizard takes over accounts, messages, folder structure, and contacts.

What is not taken over: filters, rules, and signatures. Thunderbird's filter engine is not compatible with Outlook's rule management or Apple Mail's smart mailboxes. You set up signatures later manually in Thunderbird's account settings.

Step 2: Verify the import

Check whether all folders and messages are present:

thunderbird --version

Open your imported mailboxes in Thunderbird and check whether the folder structure is intact. Compare the number of messages with your old client.

Step 3: Copy your Thunderbird profile to Linux

The Thunderbird profile contains all your imported data. Close Thunderbird on the source system and copy the profile folder:

Windows:

C:\Users\<username>\AppData\Roaming\Thunderbird\Profiles\

macOS:

/Users/<username>/Library/Application Support/Thunderbird/Profiles/

Copy the entire folder to your Linux system, for example via a USB stick or network:

rsync -av /path/to/Thunderbird/Profiles/ ~/.thunderbird/

Place the files in the same location on Linux: ~/.thunderbird/.

Step 4: Start Thunderbird on Linux

Start Thunderbird on your Linux system. It automatically recognizes the existing profile and loads your imported mailboxes.

thunderbird

If Thunderbird creates a new profile instead of loading the existing one, use the profile manager:

thunderbird -P

Choose "Create profile" and point to the copied folder.

Step 5: The IMAP alternative

Do you have your email via IMAP — Gmail, Outlook.com, an Exchange account, or a provider — then there is a simpler route. Configure the account directly in Thunderbird on Linux:

1. Open Thunderbird → Account settings → Add email account

2. Enter your email address and password

3. Thunderbird automatically recognizes known providers and fills in the server settings

Because IMAP synchronizes with the server, all your folders and messages appear automatically. No import needed, no intermediate step. This is the most reliable method when switching between operating systems.

POP3 accounts are less suitable: only locally stored email is taken over, and it may not be complete.

Verification

Check whether your old messages, folders, and settings have been transferred correctly:

find ~/.thunderbird -name "*.msf" | wc -l

This shows the number of mailbox files in your profile. Compare this with the number of folders in your old client. If the number does not match, the import was not fully successful.

Frequently asked problems

Import wizard does not show Outlook or Apple Mail as an option

The source application is not installed or not active. Install Outlook or Apple Mail on the system and make sure the account is open. Then restart Thunderbird and try again.

Folders and messages are there, but filters and signatures are missing

That is normal. Thunderbird's filter engine is not compatible with Outlook or Apple Mail. You rebuild filters via Message → Manage filters. You set signatures in Account settings → Identity → Signature.

Thunderbird on Linux opens an empty profile

The profile folder is not in the correct location. Check whether the folder ~/.thunderbird/ exists and whether the file profiles.ini is in the main folder. Move the folder if necessary and restart Thunderbird with thunderbird -P.

What this approach costs

The official import wizard is solid, but not flexible. You need the source application, you have to work on the old system, and filters and signatures you move over manually. Those who want to go directly from macOS or Windows to Linux without an intermediate step are stuck with IMAP — or with add-ons like ImportExportTools NG, which fall outside the official documentation.

The intermediate step costs half an hour, usually less than rebuilding your folder structure. And once you are on Linux, you will notice that Thunderbird's profile is just a folder: copy it and you have it, back it up and you have it. That is more than you can say for Outlook.