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How to export email from Thunderbird to .mbox

5 min read · Updated 2026-05-30

Thunderbird is the swiss-army knife of email export. Add any account over IMAP and it can write any folder to a standard .mbox file — which makes it the go-to route for providers that don't export mail themselves, like Outlook.com or a work mailbox.

Thunderbird already stores mail in mbox format under the hood, but the cleanest way to get a single, portable .mbox file is the free ImportExportTools NG add-on. Once it's installed, exporting a folder is two clicks. Because Thunderbird connects to almost any account over IMAP, this is also the standard workaround for inboxes that have no native export — connect the account, let it sync, then export.

Export a folder with ImportExportTools NG

  1. Install the ImportExportTools NG add-on. In Thunderbird, open the menu → Add-ons and Themes, search for “ImportExportTools NG,” and click Add to Thunderbird. It's a long-standing, widely used extension.
  2. Make sure the account is added and synced. If you haven't already, add your email account to Thunderbird (Account Settings → Account Actions → Add Mail Account) and wait for the folder you want to finish downloading.
  3. Right-click the folder you want to export. In the folder list, right-click your Inbox, an archive, or a receipts folder. For a full sweep, export the folder that holds the most mail.
  4. Choose ImportExportTools NG → Export folder. In the right-click menu, hover ImportExportTools NG, then pick “Export folder (with structure)” or simply “Export folder.” Either produces an .mbox.
  5. Save the .mbox to your computer. Pick a destination such as your Desktop and confirm. Thunderbird writes a single .mbox file you can drop straight onto sub-hunt.

Good to know

  • No add-on? Thunderbird's profile already stores each folder as a raw mbox file, but it lives deep in a hidden profile directory and is awkward to find — the add-on is far simpler.
  • When adding a Gmail or Outlook account, choose IMAP (not POP) so the server folders mirror correctly before you export.
  • Exporting copies the folder; it never deletes mail from the server or from Thunderbird.
  • If a folder is huge, give the sync time to finish — a partial download means a partial export.

Frequently asked questions

  • Is ImportExportTools NG safe to install?
    It's a popular, long-maintained Thunderbird extension distributed through the official add-ons site. It runs locally inside Thunderbird and doesn't send your mail anywhere.
  • Can I use Thunderbird to export Outlook or Yahoo mail?
    Yes — that's the main reason to use it. Add the account over IMAP, let the folder sync, then export it to .mbox. It's the standard route for providers without a native export.
  • What's the difference between “Export folder” and “with structure”?
    “With structure” preserves subfolders in a directory tree; plain “Export folder” writes the single folder to one .mbox. For scanning one inbox, either works.
  • Does scanning upload my mail?
    No. sub-hunt parses the .mbox entirely in your browser. Nothing leaves your device.

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