MBOX Viewer by Read Mbox
comparison · nothing is uploaded

MBOX Viewer vs Thunderbird

Thunderbird is a free, full email program. Pick it if you want to keep using the mail: reply, file and sync. This viewer is for opening an MBOX to read, search or export it, with nothing to install, no import, and no trouble with huge files.

Open your .mbox file
Free to read · runs in your browser · nothing is uploaded

Side by side

MBOX Viewer (this site)Thunderbird
What it isA reader and exporter that runs in your browserA full desktop email program
InstallNothing. Open the page and choose a file.Download and install. Optionally the ImportExportTools NG add-on.
Getting the mail inNone. The file is read where it is.Copy the file into its storage folder, or import it with the add-on.
Disk spaceNo copy is madeThe mail is copied into Thunderbird's own storage
Very large files (10 GB+)Read in small chunks and indexed onceCan be slow to index, and may freeze on very large files
Search and filterSender, subject, date range, has attachment, conversation viewFull search, saved searches, tags and folders
ExportsCSV, PDF, EML, smaller MBOX, attachments ZIP, address listEML, plus more formats with the add-on
Reply, send, syncNo. It's a reader.Yes
PrivacyNothing uploaded. Runs on your computer.Runs on your computer
PlatformsDesktop Chrome or Edge on Windows, Mac, Linux, ChromeOSWindows, Mac, Linux
CostFree to read up to 50 GB. $29 once for bulk export.Free and open source

Choose Thunderbird if…

  • You want to keep using this mail day to day: reply to it, move it into folders, or connect it to an account.
  • You want everything free, and you're comfortable installing software and importing files.
  • Your file is a manageable size and you only need EML export.

Choose this viewer if…

  • You just want to look inside an MBOX file, find something, and get on with your day.
  • The file is huge, and Thunderbird froze or the import never finished.
  • You need a spreadsheet, a PDF archive or every attachment out of it, without add-ons.
  • You're on a work computer where you can't install software.

Use both

They work well together. Open a huge Takeout file at readmbox.com, filter to the years or senders you care about, export a smaller .mbox, and give Thunderbird only that. Having trouble with the Thunderbird import?

Video: both methods, side by side

How to Open & Read MBOX Files – 3 Easy Ways (ReadMbox, Thunderbird, Apple Mail) on YouTube

Common questions

Is Thunderbird a good MBOX viewer?

Yes, if you're happy to install it and import the file. It's a full email program and free. For very large files, or if you only need to read and export, a browser viewer is quicker to set up.

Is this viewer free like Thunderbird?

Reading, searching and filtering are free for files up to 50 GB, as is exporting a single message. Bulk export and attachment extraction are a one-time $29 unlock.

Can I use both?

Yes. A common approach is to split a huge Takeout file at readmbox.com by year or sender, then import only the smaller MBOX files into Thunderbird.

Thunderbird MBOX import not working

File not showing up, wrong folder, frozen on a big Takeout file: the fixes.

Open a large MBOX file (10 GB+)

Why big Takeout files crash other apps, and how to open one without importing anything.

MBOX file won't open

The six usual reasons, from "still in the zip" to "too big for the app", and the fix for each.

I just downloaded Google Takeout. Now what?

Which file holds your mail, why it's one giant .mbox, and how to open and search it.

Ready? Your file stays on your computer.

Open your .mbox file