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. Windows Outlook cannot open a Mac OLM file, so the data has to be moved out of the Mac format first. If you still have the Mac, a free IMAP bridge carries the mail across, with contacts and calendar exported separately. If you only have the .olm file, a converter turns it into a PST on Windows, keeping mail, calendar and contacts.
On this page
Why Outlook cannot just open an OLM?
Start with the fact that explains all the difficulty, because most guides skip it. Windows Outlook cannot open or import an OLM file. There is no menu for it and no add on that changes that, because Microsoft never built one.
OLM is the format Outlook for Mac uses when it exports an archive. Outlook on Windows keeps its data in a completely different format, the PST. The two were never made to read each other, so handing a .olm file to Windows Outlook simply does not work. That is not a setting you have missed, it is a genuine gap between the two applications. Everything below is really about the same thing, getting your data out of the Mac format and into one Windows Outlook understands.
Two different formats that were never built to read each other.
“OLM and PST are two unrelated container formats, one from Outlook on the Mac and one from Outlook on Windows, and nothing in either application bridges them, so the data has to be carried across by another route. If that route is IMAP, remember it is a mail protocol, it moves messages faithfully but it has no concept of a calendar appointment or a contact card, so those need handling separately. Reading the OLM directly is the only path that keeps the whole mailbox together, which matters most when the Mac it came from is already gone.” Shubham Dixit, Email Migration reviewer (draft, pending approval)
Which route you need?
There are two honest ways to do this, and which one applies to you comes down to a single question, do you still have the Mac the OLM came from, with Outlook for Mac working on it.
If you do, you can move the mail across for free by routing it through an IMAP account, no purchase needed. If you do not, and all you have is the .olm file sitting on a Windows PC, that free route is closed to you, because it depends on Outlook for Mac being able to send the mail out. In that case a converter that reads the .olm directly is the way, and it has the side benefit of carrying the calendar and contacts too. The two sections below cover each path.
The Mac decides the route. With it, bridge free. Without it, read the file.
The free way, if you still have the Mac
If Outlook for Mac still runs on the machine, you can move the mail across without paying for anything, by using an IMAP account as a staging post. Gmail works well for this, and so does any IMAP mailbox you control.
Add an IMAP account in Outlook for Mac. In Gmail or your chosen provider, make sure IMAP is switched on, then add that account inside Outlook for Mac through Preferences and Accounts.
Copy your mail into it. Create a folder under the IMAP account, then select the mail from your Mac Outlook folders and copy it in. Outlook uploads it to the server, which can take a while for a large mailbox, so let it finish syncing.
Pull it down in Windows Outlook. Add the same IMAP account to Windows Outlook, and the mail appears, fully, attachments included. If you want it stored locally as a PST rather than left on the server, drag it from the IMAP folders into a local Outlook folder.
Two honest limits to plan around. This needs the Mac with Outlook for Mac working, and IMAP moves mail only, so your contacts and calendar do not travel this way. Export those separately on the Mac, contacts as a vCard and the calendar as an ICS file, then import them into Windows Outlook.
The direct way, from the OLM file itself
If the Mac is gone, or you simply want the whole mailbox moved in one step with the calendar and contacts kept alongside the mail, a converter reads the .olm file directly on Windows. The PCDOTS OLM Converter opens one or many OLM files, previews the contents, and writes a PST containing the mail, calendar, contacts and notes together, on your own PC with nothing uploaded. Its real value is exactly the two things the free bridge cannot manage, it works from the .olm file with no Mac involved, and it carries the non mail items that IMAP leaves behind. There is a free version to try on your own file first.
The direct route, from the .olm file to a PST on Windows.
Here are the steps with the screens.
Step 1. Install and run the converter on Windows, open the menu, choose Email Data Files and the Outlook Mac file option, and load your OLM files.
Step 2. Preview any folder or message to confirm the contents, then select what you want.
Step 3. Open the Export menu and choose PST.
Step 4. Choose a destination folder and click Save to build the PST.
Getting the PST into Outlook
However you produce the PST, the last step is the same and it is the one part Windows Outlook does natively. In Outlook, go to File, Open and Export, then Import/Export, choose to import from another program or file, pick Outlook Data File (.pst), and point it at your file. Your Mac mail then sits in Windows Outlook as ordinary folders.
If your data is actually headed for Microsoft 365 rather than a desktop Outlook, there is a separate guide to move OLM files to Office 365. You can also open a finished PST with a free PST file viewer before importing it.
The methods compared
Match the route to what you still have and what you need moved.
| Method | Best for | Good to know |
|---|---|---|
| IMAP bridge | You still have the Mac, free | Mail only, do contacts separately |
| OLM converter | Only the .olm file, or the full mailbox | No Mac needed, keeps calendar too |
| Import the PST | The final step, free | Native Outlook Import/Export |
Frequently asked questions
Can Windows Outlook open an OLM file?
No. OLM is Outlook for Mac’s format and Windows Outlook uses PST, with no native import between them. The data has to be moved across another way first.
How do I import OLM to Windows Outlook for free?
If you still have the Mac, add an IMAP account like Gmail in Outlook for Mac, copy your mail into it, then add the same account in Windows Outlook. The mail syncs down, attachments included.
Does the free method move my contacts and calendar?
No. IMAP carries mail only. Export contacts as a vCard and the calendar as an ICS file on the Mac and import those into Windows Outlook separately, or use a converter that keeps everything together.
How do I import an OLM if I no longer have the Mac?
Use a converter that reads the .olm file directly on Windows and writes a PST. This is the only route that works from the file alone, and it keeps the mail, calendar and contacts.
Which Outlook versions does this work with?
Any modern Windows Outlook, since the final step is the standard PST import. A PST built from your OLM imports into Outlook 2013, 2016, 2019 and later the same way.
Will attachments come across?
Yes. Both routes preserve attachments. The IMAP bridge moves full messages, and a direct conversion writes them into the PST with the mail.
It comes down to whether you still have the Mac
The whole decision rests on one thing. If the Mac is still around with Outlook for Mac working, bridge the mail across through an IMAP account for free, and export the contacts and calendar separately to finish the job. If the Mac is gone and you are left holding just the .olm file, or you would rather move the entire mailbox in one pass with the calendar and contacts intact, a converter that reads the file directly is the route to take. Either way the final step is the same easy one, importing the PST into Windows Outlook, and your Mac mail lands where you need it.
