PubRescue What is an .mbox file?
An .mbox file is a whole mailbox in one file: every message in a folder, one after another. It's what you get when you export mail from many services and programs, and it's a common way to keep an archive of an old account.
How to open an .mbox file
- Drop the .mbox file onto the box at the top of this page, or click Choose files.
- Wait for the index. A progress bar shows while the viewer reads through the mailbox. Big files take a little longer.
- Browse the list. Messages are listed newest first. Click one to read it in the reading pane. On a phone, tap a message to open it and use the Back button to return to the list.
- Search. Type in the search box to filter by subject, sender, recipients and date instantly. Tick Search message text too to look through the full text of every message (slower, with a progress bar).
- Save what you need. Tick messages, or use Select all for all shown results, then choose Save selected as PDF or Export selected as .eml (ZIP). Attachments of the open message can be downloaded too.
Where your .mbox file comes from
- Gmail export from Google Takeout. In Takeout, choose Mail, create the export, download it and unzip it. The mailbox is in Takeout/Mail, often named All mail Including Spam and Trash.mbox.
- Thunderbird. Each folder is stored as a file without an extension, such as Inbox or Sent, in your profile's Mail or ImapMail folder. Those files are mbox. Choose one here; if the file picker greys it out, drag and drop it instead, or rename a copy to add .mbox.
- Apple Mail. Mailbox > Export Mailbox creates a folder named something like Inbox.mbox. The mailbox itself is the file called mbox inside it. In Finder, right-click the folder, choose Show Package Contents, and pick that inner file.
Big mailboxes are fine
The viewer reads the file in pieces rather than loading all of it into memory. That's why a multi-gigabyte Takeout export can open in a browser tab without uploading anything. Large mailboxes are more comfortable on a computer than on a phone, but they work in mobile browsers too.
Reading messages
HTML emails show as they were designed, in a locked-down frame where no scripts run. Pictures loaded from the internet are blocked by default, because they can be used for tracking; click Load remote images to show them. Pictures embedded in the email show normally. Attached emails open in the viewer as well.
Your email stays on your computer
The viewer runs entirely in your browser. Your mailbox is read on your device and is never uploaded to our server or stored. Only this page and its scripts come from us. Searching, reading and exporting all happen on your computer.
What to expect
- Up to 500 messages per PDF. For more, save them in batches; search helps you pick each batch. See MBOX to PDF.
- Exporting thousands of messages as a ZIP at once uses a lot of memory. Do it in batches.
- Exported .eml files open in Apple Mail, Outlook and Thunderbird.
- Encrypted messages aren't decrypted; signed ones display without checking the signature.
- Damaged parts of a mailbox may be skipped or show oddly.