Thunderbird Storage Location: Where Emails Are Kept

Thunderbird stores your emails, address books, and settings in a profile folder on your computer, not inside the program’s installation files. This folder is separate from the application itself so that updates and reinstalls don’t delete your data. The exact location varies by operating system, but you can always find it through Thunderbird’s built-in troubleshooting page.

Profile Folder Basics

Thunderbird uses a profile system to keep each user’s data isolated. A profile is a collection of files and folders that contain everything about your mail setup: your messages, contacts, passwords, filters, and preferences. The default profile is named xxxxxxxx.default, where xxxxxxxx is a random string of eight characters. This naming prevents conflicts if you create multiple profiles.

Inside the profile folder, the most important items are:

• Mail/ – contains subfolders for each email account; messages are stored as individual files (one per message) in a subfolder named after the account’s server.
• ImapMail/ – holds cached copies of IMAP messages so you can read them offline.
• abook.sqlite and history.sqlite – your address books (personal and collected addresses).
• prefs.js – stores all your settings and preferences in text form.
• cert9.db – stores security certificates used for encrypted connections.

Locations by Operating System

The default profile location depends on your OS. Here are the standard paths (for Thunderbird 115 and later):

• Windows: %APPDATA%\Thunderbird\Profiles\xxxxxxxx.default (typically C:\Users\[YourUsername]\AppData\Roaming\Thunderbird\Profiles\...)
• macOS: ~/Library/Thunderbird/Profiles/xxxxxxxx.default (the Library folder is hidden by default; press Option while clicking Finder’s Go menu to see it)
• Linux: ~/.thunderbird/xxxxxxxx.default (the dot makes it hidden; press Ctrl+H in your file manager to show hidden files)

Note that on Windows, the path uses AppData\Roaming (not Local) because Thunderbird stores user data there. If you installed Thunderbird from the Microsoft Store, the path might be under %LOCALAPPDATA% instead, but that’s rare.

How to Find Your Exact Profile Path

If you have multiple profiles or have moved your profile manually, the default path may not apply. The surest way to locate your current profile:

1. Open Thunderbird.
2. Click the menu button (three horizontal lines) and select Help > Troubleshooting Information.
3. In the Application Basics section, look for Profile Folder.
4. Click the Open Folder button (Windows/Linux) or Show in Finder (macOS) next to it. This opens the exact folder in your file manager.

Alternatively, you can type about:support in the address bar and press Enter – it opens the same page. The profile folder path is also stored in a file called profiles.ini located in the Thunderbird application data directory (e.g., %APPDATA%\Thunderbird\ on Windows).

What Each Subfolder Contains

Understanding the folder structure helps when you need to back up or move your data.

• Mail/ – For POP3 accounts, messages are downloaded and stored here permanently. Each account gets a folder named after the mail server (e.g., pop.example.com). Inside, you’ll find the actual messages as files with no extension, plus an Inbox.msf file (the index).
• ImapMail/ – For IMAP accounts, Thunderbird keeps a local cache of messages so you can read them without an internet connection. The folder structure mirrors the server’s folders (e.g., imap.example.com/INBOX). These are not your primary copy – the server holds the originals.
• Mail/Local Folders – This is where messages you store in “Local Folders” (like drafts or archives) live, regardless of your account type.
• calendar-data/ – If you use the Lightning calendar, your events and tasks are stored here as .ics files.
• extensions/ – Installed add-ons are stored here, but only their settings; the add-on code itself lives in the Thunderbird installation directory.

Backing Up and Moving Your Profile

Because all your data is in one folder, backing up is simple: copy the entire profile folder to an external drive or cloud storage. To move to a new computer, copy the folder to the same location on the new machine (or use the Profile Manager to point to it).

If you want to move the profile to a custom location (e.g., a D: drive to save space on C:), you can:

1. Close Thunderbird.
2. Move the profile folder to the new location.
3. Edit profiles.ini in the Thunderbird application data directory. Change the Path= line to the new full path, and set IsRelative=0 (so Thunderbird treats it as an absolute path).

Make sure the new drive is always connected when you start Thunderbird; otherwise, it may create a new profile and you’ll see an empty mailbox.

Common Problems and Fixes

Users often accidentally delete or move the profile folder, leading to “profile missing” errors. Here are typical issues and how to resolve them:

• “Thunderbird is already running but not responding” – This usually happens because a lock file (parent.lock or .parentlock) remains after a crash. Delete that file from the profile folder while Thunderbird is closed.
• Can’t find the profile folder – If you’ve hidden file extensions or system files, the folder may be invisible. In Windows Explorer, enable “Show hidden files and folders” in View options. On macOS, use Cmd+Shift+. to show hidden files.
• Emails disappeared after reinstall – Reinstalling Thunderbird doesn’t touch your profile, but if you uninstalled the program and chose to remove user data (some uninstallers offer this), the profile is deleted. Always back up the profile before uninstalling.
• Profile folder is huge – Over time, IMAP cache and old messages can consume gigabytes. You can compact folders (right-click a folder > Compact) to remove deleted message remnants. For IMAP, you can also reduce cache size in Settings > Privacy & Security > Content Blocking (but that’s for web content).

Frequently Asked Questions

Q: Can I change where Thunderbird stores emails?
Yes. You can move the entire profile folder to a new location and update profiles.ini as described above. Alternatively, for individual accounts, you can set a different “Local Directory” in Account Settings > Server Settings > Local Directory for POP3 accounts, but this is not recommended for IMAP.

Q: How do I export my emails from Thunderbird?
Exporting messages can be done by copying the profile folder (for backup) or by using the built-in “Export” feature (Tools > Export) which creates an MBOX file. For individual messages, you can also drag them to a folder in Windows Explorer to save as .eml files.

Q: Why are my emails stored as files without extensions?
Each message is stored as a plain text file with no extension. Thunderbird reads these files directly. If you open one with a text editor, you’ll see the raw email source (headers and body). The .msf files are index files that speed up searching.

Q: Does Thunderbird store emails on the server or locally?
It depends on your account type. POP3 downloads messages to your computer and (by default) deletes them from the server. IMAP keeps messages on the server, and Thunderbird stores only a local cache. If you use IMAP, your emails are safe even if you lose your hard drive.

Q: How do I back up only my address book?
You can export your address book as a .vcf or .csv file: open Address Book (Ctrl+Shift+B), select the address book, then Tools > Export. Or simply copy the abook.sqlite file from your profile folder.

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