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MBOX vs PST: which email archive format is which?

4 min read · Updated 2026-05-30

Export your email and you'll get one of two files: an .mbox or a .pst. They do the same job — archiving a mailbox — but they come from different worlds. Knowing which is which saves you from feeding the wrong file to a tool that can only read one of them.

MBOX is the open, cross-platform format: a single plain-text file that concatenates every message, used by Thunderbird, Apple Mail, Google Takeout, and most non-Microsoft mail software. PST (Personal Storage Table) is Microsoft's proprietary format, used by the Outlook desktop app to store mail, calendar, and contacts in one binary database file. Both archive your mail; only one is an open standard.

The practical differences

At a glance

  • Openness: MBOX is an open, documented format readable by many programs; PST is Microsoft-specific and really only fully understood by Outlook.
  • What it stores: MBOX holds email messages only; PST can also bundle calendar entries, contacts, and tasks.
  • Where you meet it: you get MBOX from Gmail/Takeout, Apple Mail, and Thunderbird; you get PST from the Outlook desktop app's Import/Export.
  • Portability: an MBOX will open in many tools years from now; a PST is tied to the Microsoft ecosystem.

Which one do you have?

Look at the file extension. If it ends in .mbox (or, on a Mac, it's a folder ending in .mbox), it's the open format and tools like sub-hunt.com can read it directly. If it ends in .pst, it came from Outlook and you'll need to convert it first — most mail tools, including sub-hunt, don't read PST because the format is proprietary.

Converting PST to MBOX

If you've got a .pst and need an .mbox, the easiest route avoids dedicated converter software entirely:

  1. Connect the live account in Thunderbird. If the Outlook account still exists, add it to Thunderbird over IMAP and export the folder to .mbox — no conversion needed. See the Outlook export guide for the full steps.
  2. Or import the PST, then export. If you only have the .pst file, import it into Outlook (or a tool that reads PST), then export or re-sync the mail through Thunderbird to produce an .mbox.
  3. Use a converter as a last resort. Dedicated PST-to-MBOX converters exist, but they're extra software handling your mail; prefer the Thunderbird route when you can.

Frequently asked questions

  • Can sub-hunt read a .pst file?
    No. sub-hunt reads the open .mbox format. PST is Microsoft's proprietary format, so you'll need to convert it to .mbox first — usually by routing the account through Thunderbird.
  • Is MBOX or PST better for archiving?
    For long-term archiving, MBOX is the safer choice because it's an open format many programs can read. PST is fine inside the Microsoft world but locks your archive to Outlook.
  • Does converting lose any email?
    A clean conversion preserves the messages and their headers. Calendar entries and contacts in a PST won't carry into an MBOX, since MBOX only stores email.

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