Convert PST to MBOX

Why convert PST to MBOX?

A .pst file is Outlook's own format. Most other mail programs can't read it, but many can import MBOX, a standard format that stores a folder of messages in one file. Converting is the usual way to move an Outlook mailbox into Apple Mail or Thunderbird, or to keep an archive in a format more tools understand.

How to convert a .pst file to MBOX

1. Drop the .pst or .ost file onto the box at the top of this page, or click Choose files.
2. Pick a folder in the Folder drop-down, such as Inbox. The drop-down shows the folder tree, indented, with message counts.
3. Choose what to export. To export the whole folder, select nothing. To export only some messages, tick them, or search and use Select all.
4. Click Export as MBOX. The viewer builds one .mbox file and your browser downloads it. Large folders are written in pieces, so big exports work.
5. Repeat for each folder you want to keep, such as Sent Items and your own subfolders.

Import the .mbox into Apple Mail

1. In Apple Mail, choose File > Import Mailboxes.
2. Select Files in mbox format and click Continue.
3. Pick the .mbox file you downloaded and finish the import.
4. The messages appear in a new mailbox under On My Mac. Rename it or drag messages where you want them.

On a Mac? See also how to open a .pst file on a Mac.

Import the .mbox into Thunderbird

Thunderbird imports .mbox files with an import add-on, such as ImportExportTools NG. Install it from Thunderbird's add-ons page, then right-click a folder under Local Folders and use the add-on's import option for mbox files. Pick the .mbox file you downloaded; it becomes a folder in Thunderbird.

One folder at a time

Each export makes one .mbox file from one folder, or from the messages you selected. The folder structure of the whole .pst isn't recreated in a single export, so export folder by folder and name the files as you go. The Inbox and Sent Items are usually the ones that matter most.

Big .pst files are fine

The viewer reads the .pst in pieces, only what it needs, and writes the .mbox in pieces too. A multi-gigabyte file opens quickly and isn't loaded into memory all at once. You do need free disk space for the downloaded .mbox file, which can be about as large as the folder itself.

Your email stays on your computer

The converter runs entirely in your browser. Your .pst file is read on your device and is never uploaded to our server or stored. Only this page and its scripts come from us. The .mbox file is made on your computer and saved straight to your downloads.

Limits

• Contacts, calendar items and tasks aren't converted to vCard or iCalendar.
• Encrypted (S/MIME) messages aren't decrypted.
• Damaged parts of a corrupt file are skipped; the viewer tells you how many.
• .ost files from some setups may not open.
• Need separate files instead? Export selected as .eml (ZIP) makes one .eml per message, up to 65,535 messages and 4 GB per ZIP.