Open MBOX files – without Thunderbird, on Mac and Windows
An MBOX file is a whole mailbox in a single file: every email is stored one after another, each starting with a “From …” line. Thunderbird, Apple Mail’s mailbox export and Google Takeout all use it. Mail Archive opens the file and shows the message list with folders and every email with its attachments. Viewing is free.
Available on the Mac from version 1.3. The Windows version with these features is coming soon to the Microsoft Store.
Where your MBOX file comes from
Thunderbird
Each folder is a file without an extension, such as “Inbox” in your profile folder. Subfolders sit in “Inbox.sbd”. Mail Archive handles both.
Apple Mail export
“Export Mailbox …” creates a folder “Name.mbox” with a file called “mbox” inside. You can open the whole folder.
Google Takeout
Your Gmail export contains one large .mbox file with all your mail, e.g. “All mail Including Spam and Trash.mbox”.
Other apps
Many email clients and webmail services export .mbox or .mbx. Mail Archive checks the content, not just the extension.
How to open an MBOX file
Get Mail Archive
Free for Mac (App Store) or Windows (Microsoft Store). You don’t need an email account to view files.
Open the file
Click “Open file …” at the bottom left (or press ⌘O / Ctrl+O) and pick the .mbox file. Drag Thunderbird files without an extension, or whole folders, straight into the window.
Browse the mailbox
Mail Archive reads the mailbox and lists every email, newest first. Use “All folders” to filter by folder; the search field finds subject or sender.
Read an email
Click a message to see its text and attachments. Open or save attachments as you like. External images and tracking pixels are not loaded.
Free: viewing MBOX files is unlimited in the free version.
View your Apple Mail library directly
Apple Mail doesn’t keep your mail as MBOX but as individual .emlx files in ~/Library/Mail/V10. Mail Archive reads that folder too, without exporting first, and shows every mailbox with its folders.
- In Finder press ⇧⌘G and enter
~/Library/Mail. - Drag the V10 folder (or a single mailbox inside it) into the Mail Archive window.
- To import permanently, choose “Apple Mail library” under “Import emails” (Pro).
Why won’t my MBOX file open?
MBOX is an old, open format, yet hardly any app will simply display someone else’s MBOX file:
- No default app: neither Windows nor macOS ships with anything that opens .mbox on a double-click. Apple Mail and Outlook don’t open it directly.
- Import, not view: Apple Mail and Thunderbird can only import MBOX. The messages end up in your mail client, and big files take a while.
- No extension: Thunderbird folders are just called “Inbox” or “Sent”, so Windows doesn’t know what to open them with.
- Size: a Google Takeout export is often several gigabytes. Text editors give up, and even when they don’t, you only see raw text with Base64-encoded attachments.
No upload, no cloud
An MBOX export often holds years of correspondence. Online MBOX viewers want you to upload it to their server. Mail Archive reads the file on your computer. Nothing is uploaded, and you don’t need an account with us.
The MBOX file itself is never modified. Mail Archive only reads it.
What’s free and what Pro adds
| Feature | Free | Pro (€14.99 one-time) |
|---|---|---|
| View MBOX files, Thunderbird folders, Takeout | ✓ | ✓ |
| View the Apple Mail library (Mac) | ✓ | ✓ |
| Filter by folder, search subject and sender | ✓ | ✓ |
| “Add to archive” with folder structure | – | ✓ |
| Save a single email as PDF | – | ✓ |
Emails already in your archive are skipped. All plans are one-time purchases, no subscription.
Add MBOX to your archive
If you want to keep the emails and search them, add them to your local archive, straight from the viewer or through the importer.
From the viewer
Click “Add to archive” at the top. The mailboxes become folders under “Imported files”.
Or via import
Under Accounts, click “Import emails (EML, MBOX)” on the account you want and choose “MBOX file” or “Folder with MBOX mailboxes”, e.g. Thunderbird’s “Local Folders”.
Done
Mail Archive reports how many emails were imported and how many were already there. Full-text search then covers everything.
To be fair: other options
- Thunderbird (free): with an import add-on, Thunderbird can read MBOX files. A good choice if you use Thunderbird anyway.
- Apple Mail: “File › Import Mailboxes …” brings MBOX files into Apple Mail. The messages then live in your mail client.
- A text editor: fine for a quick look at small files, but attachments and non-ASCII characters show up as encoded text.
Mail Archive fits when you just want to look inside the file without importing it into a mail client, or when you want a permanent, searchable archive on your own computer.
MBOX questions
Is there a free MBOX viewer?
Yes. Mail Archive lets you view MBOX files for free with no limit: message list, folders, every email with attachments. Only “Add to archive” needs Pro (€14.99 one-time).
How do I open a Google Takeout mail export?
Unzip the download from Google and open the .mbox file from the “Mail” folder with “Open file …”. Large files are read with a progress indicator.
Where does Thunderbird keep its MBOX files?
In your profile folder under “Mail” or “ImapMail”. Thunderbird shows the profile folder under Help › Troubleshooting Information. Drag a folder such as “Local Folders” into Mail Archive to see every mailbox in it.
Do I need Apple Mail or Thunderbird?
No. Mail Archive reads the file itself, and you don’t need an email account to view it.
Does it work on Windows?
Yes. Opening MBOX files works the same on Mac and Windows. Only the Apple Mail library is, naturally, Mac only.
Will my MBOX file be changed?
No. Mail Archive only reads it. When you add it to the archive, the emails are copied and the original file stays as it is.
Mail Archive does more
Your mailbox, on your computer
Get Mail Archive for free and view MBOX files right away. Add them to your archive with Pro, €14.99 one-time.