Written by Jennifer Walsh. Reviewed for technical accuracy by Shubham Dixit, Independent Expert in Email Forensics and Data File Conversion.
Shubham is an independent external reviewer and not an employee of PCDOTS.
Quick answer. The Windows 10 Mail app cannot import files, it does not read MBOX, and Microsoft has now replaced it with the new Outlook for Windows. The honest way to see MBOX mail there is to route it through an account, get the MBOX into a Gmail or Outlook.com mailbox over IMAP, then add that account to the app. To just read the MBOX, a free viewer opens it.
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Can you import MBOX into Windows 10 Mail?
Short answer, no, and it is worth understanding why before you waste time hunting for an import button that does not exist. The Windows 10 Mail app has no file import at all, and it does not understand the MBOX format. It is not that kind of program, it is a viewer that shows the mail from accounts you add to it, like Outlook.com, Gmail or any IMAP account. There is no place to hand it a file.
There is a second reason too. Microsoft has retired the Windows Mail app. Support for Mail, Calendar and People ended at the close of 2024, the app can no longer send or receive new mail, and Microsoft has moved everyone to the new Outlook for Windows. So rather than chase a dead end, the sensible goal is to get your MBOX mail into an account that your Windows mail app, old or new, will display. That is the route below, and it keeps working whichever app you land on.
No file goes into the app, the mail arrives through an account the app displays.
“People picture the Mail app like an old desktop client with an import menu, but it was never that, it just mirrors whatever accounts you connect. So the trick is never to import into the app, it is to land the mail in an account and let the app show it. That approach has aged well, because Microsoft has folded the Mail app into the new Outlook, and the account route works exactly the same there. Get the MBOX into a mailbox, add the mailbox, done.” Shubham Dixit, Email Migration reviewer (draft, pending approval)
The account route, the real way
The idea is simple, put the MBOX mail into a mailbox the app can connect to, then connect it. Here is the free version with a mail client as the go-between.
Add your cloud account to Thunderbird. Pick a mailbox you want the mail to live in, a Gmail, Outlook.com or other IMAP account, and add it to Thunderbird. Sign in with the account’s own method, Gmail and iCloud use an app password, Outlook.com uses a Microsoft sign-in.
Import the MBOX and drag it up. Use the free ImportExportTools NG add-on to import your MBOX into a local Thunderbird folder, then drag those messages into a folder under the cloud account. Because it is IMAP, they upload to the mailbox.
Add the same account to your Windows mail app. Open the new Outlook for Windows, or the Mail app while it still opens, and add that same account. The mail you uploaded appears, because the app is simply showing the mailbox.
Windows 10 Mail or Windows Live Mail?
A lot of people search for one of these while meaning the other, so it is worth a quick word. They are different programs.
Windows 10 Mail is the modern app built into Windows 10 and 11, account based, no file import, and now folded into the new Outlook. Windows Live Mail is the older desktop client from the Windows Essentials era, long discontinued but still on some machines. If you truly mean Live Mail, it does not read MBOX either, but it can import EML files, so you would convert the MBOX to EML first and import those. For the modern Mail app, the account route above is the way.
Check which one you actually have before you start.
If you only want to read the MBOX
Sometimes the real need is not the Mail app at all, you just want to open the MBOX and read what is inside on a Windows PC. In that case skip the accounts entirely. A free MBOX file viewer opens the file and shows the messages with attachments, and Thunderbird with the ImportExportTools NG add-on will do the same. Our guide to open MBOX files on Windows walks through the options.
The bulk way, a tool
The free route works, but dragging a large MBOX through Thunderbird is slow, and it needs the client set up. A converter uploads the MBOX to your chosen mailbox over IMAP directly, then that account shows in your Windows mail app. The PCDOTS MBOX Converter loads MBOX files or a whole folder, including an orphaned one, and sends the mail into a Gmail, Outlook.com or other IMAP mailbox in bulk, keeping attachments and folder structure. It runs on Windows and signs in with the mailbox’s own method. A free version uploads the first ten items per folder so you can test it first.
The tool route, for a large MBOX going into an account.
Here are the steps with the screens.
Step 1. Install and run the converter on Windows, then open the menu.
Step 2. Choose Email Data Files, MBOX, and add your files or folder.
Step 3. Open the Export menu and select IMAP.
Step 4. Enter your mailbox address and sign-in, then Save to upload. Add that same account to your Windows mail app.
For the read-only options see open MBOX files on Windows, and for the client route in depth see import MBOX to Thunderbird.
The methods compared
All three end with the mail in an account your Windows mail app displays, or simply readable.
| Method | Best for | Good to know |
|---|---|---|
| Thunderbird into a cloud account | Free route into the app | Then add the account to the app |
| Free MBOX viewer | Just reading the MBOX | No account or app needed |
| MBOX Converter tool | Large or orphaned MBOX | Windows, uploads over IMAP |
Frequently asked questions
Can the Windows 10 Mail app import an MBOX file?
No. The app has no file import and does not read MBOX. It only shows mail from accounts you add, so you route the MBOX into an account and add that account.
Is the Windows 10 Mail app still around?
Microsoft ended support for the Mail and Calendar apps at the end of 2024 and replaced them with the new Outlook for Windows. The account route works the same in the new Outlook.
How do I get MBOX mail to show in the Mail app?
Upload the MBOX into a Gmail, Outlook.com or IMAP mailbox, through Thunderbird or a tool, then add that same mailbox to the app so it displays the messages.
Is Windows 10 Mail the same as Windows Live Mail?
No. Windows Live Mail is an older desktop client. It does not read MBOX either, but it can import EML, so convert the MBOX to EML first if that is what you have.
I only want to read the MBOX, what is easiest?
Open it with a free MBOX viewer, or in Thunderbird with the ImportExportTools NG add-on. Neither needs the Mail app or an account.
Do attachments and folders survive?
Yes. Uploading over IMAP keeps attachments and the folder structure with the messages, whether you drag them in Thunderbird or use a tool.
The account is the real way in
The honest takeaway is that you never import a file into the Windows 10 Mail app, you feed it an account. Get your MBOX mail into a Gmail, Outlook.com or IMAP mailbox, then connect that mailbox and the app shows everything. What makes this worth doing properly is where it leads next, because the Mail app is becoming the new Outlook for Windows, and an account you set up today carries straight over to it, and to your phone, and to the web. Put the mail somewhere that travels with you, and the app you happen to open is just a window onto it.
