You exported your mail from Gmail, Thunderbird or Apple Mail, and now you have a .mbox file. Then you try to open it in Outlook and hit a wall: Outlook doesn't read MBOX. It wants PST.
The usual fixes aren't great. Desktop converters are mostly Windows installers with a "demo" that won't actually export. "Online" converters work by uploading your entire mailbox to someone's server, which is a lot to hand over to a company you know nothing about.
Here's the way I do it now: open the MBOX in a browser tab, filter it if you want, export to PST, and import into Outlook. Your mail never leaves your computer.
What you need
- Your
.mboxfile (from Google Takeout, Thunderbird or Apple Mail) - A desktop browser — Chrome or Edge work best
- Microsoft Outlook
No install, no account, no upload.
If you still need the MBOX file: in Google Takeout, select Mail, download the export and unzip it — the .mbox is inside. Thunderbird keeps its MBOX files in your profile folder.
Step 1: Open your MBOX file in the browser
Go to readmbox.com, scroll down to the file picker, and click Choose an .mbox file. Pick your file.
The file is read locally by your browser. Nothing is sent to a server — you can confirm that yourself by opening your browser's Network tab while it loads and watching no mail go out.
Large files are fine. Big Takeout exports run into tens of gigabytes; the viewer reads them in chunks. The first open takes a pass to index the file, then it's quick.
Step 2: Find the emails you want (optional)
Once it loads, you can click through messages one by one, or narrow things down by:
- Sender
- Subject line
- Date range
- Whether the email has an attachment
This is useful if you don't want 15 years of newsletters landing in Outlook. Filter down to, say, everything from one client in 2024, and export only that.
Step 3: Export to PST
Click Export and choose PST as the format. You get two choices:
- Entire mailbox — everything in the MBOX file
- Current view — only the emails matching the filters you set in Step 2
Click Export and the .pst file downloads to your computer.
Step 4: Import the PST into Outlook
In Outlook:
- Go to File → Import.
- Select Outlook for Windows archive (.pst) and click Continue.
- Choose the PST file you just downloaded.
- Wait — it can take a few seconds to a few minutes depending on size — then click Finish.
You'll see a new folder in Outlook named after the PST file, with your exported emails inside.
Watch the walkthrough
The whole process takes about a minute and a half on video: How to convert MBOX to PST — YouTube
Why convert in the browser instead of an "online converter"?
Most online MBOX converters have to upload your file to process it. That means a copy of every email you've sent and received sits, at least for a while, on a server you don't control.
readmbox.com works differently: the conversion code runs in your browser, so there's no server for your mail to go to. The page does use Google Analytics (that's disclosed on the site), but your mailbox itself never leaves your machine.
FAQ
Does it work on my phone? No — it's built for desktop browsers. Large mailboxes need a desktop's memory.
Is it free? Opening and reading your MBOX file is free. Bulk export is a one-time $29 unlock — no subscription.
Can I export to other formats? Yes. Besides PST, you can export to CSV (for Excel or Google Sheets), PDF, EML, split MBOX, and pull out all attachments as a ZIP.
My MBOX is huge. Will it open? Files of tens of gigabytes work. Expect the first open to take a few minutes while it indexes.
Try it
Got an MBOX that needs to go into Outlook? Open it at readmbox.com. If you get stuck or have a suggestion, let us know — we read everything.
