Switching from a Mac to a Windows PC should be a simple process, but your email history might make it shockingly hard. When you use Outlook for Mac, your emails are saved in .OLM files. That format cannot be read by Outlook for Windows. It expects PST files. This mismatch leaves many people left staring at an archive they cannot open on their new system.

We’ll explain exactly what OLM files are, where to find them on your Mac, and how to convert them to PST so you can import everything into Outlook on Windows without missing a single email in this article.

What Is an OLM File? 

OLM means Outlook for Mac Archive. This is the file format you use to export your mailbox data from Outlook for Mac. Under the hood, an OLM file is effectively a ZIP archive of XML files describing your emails, folders, contacts, calendar entries, and attachments.

This XML-based structure is great in the Mac ecosystem but entirely incompatible with Outlook for Windows. The Windows version of Outlook utilizes PST (Personal Storage Table), a binary format with a completely different underlying structure. There is no built-in utility in any version of Outlook to convert between the two.

Why Do You Need to Convert OLM to PST?

The most prevalent situations are the following:

• Switching from Mac to PC. Moving to a new PC and want to take your whole email history with you? Your Mac archive is OLM, but the new machine requires PST.
• Standardization of Firms. Your organization is running on a Windows-based infrastructure and needs all email archives in PST format for compliance, backup, or migration reasons.
• Cross-platform sharing of archives. You’ve got a coworker on a Mac who needs to send their email archive over to someone on Windows, or vice versa.
• Migrations of IT departments. The organization is moving from a heterogeneous platform to a standardized Windows environment, and the entire team has dozens of OLM files to convert.

The fundamental issue is the same in both cases: two versions of the same email application use incompatible file formats.

Where Are OLM Files Stored on Mac?

OLM files are not created automatically. You will have to export them manually from Outlook for Mac. Here’s how to construct your OLM archive:

• Open Outlook for Mac
• Click Tools > Export.
• Choose what you'd want to export: e-mails, contacts, calendar events, tasks, or all of the above.
• Select the destination folder on your Mac, and then click Export.
• Outlook will create an .olm file with everything you chose.

By default, it will save to your Documents folder or Desktop, but you can save it wherever you choose. Make a note of where you saved it, as you'll need to find the file for the next step.

Solution: How to Convert OLM to PST using The Software

MailVita OLM to PST Converter Mac is a complete online, cloud-based email converter for OLM to PST conversion right from your browser. There is no program to download, no desktop application to install, and no license to purchase. The whole procedure is running on remote servers, so it’ll work on any device, whether you’re still using your Mac or already using your new Windows PC.

Conversion Process — Step by Step

1. Find your OLM file. Locate the .olm file that you exported from Outlook for Mac. If you haven't exported yet, perform the instructions in the section above.
2. Open .com in any browser. To upload your OLM file, drag and drop it here or click to browse and pick it. The file is transmitted securely over HTTPS.
3. Choose PST as the export format. Select PST as the export type. The software will scan the OLM file and export all of it into a well-structured PST archive.
4. Download PST file. Once the conversion is complete, download the resulting PST file to your Windows PC (or to whatever destination you like). 
5. Import to Outlook for Windows. Open Outlook on your Windows system, go to File > Open & Export > Import/Export, pick Import from another program or file, choose Outlook Data File (.pst), and browse to the PST file you downloaded. Outlook will import all your emails, folders, and attachments. 

What is retained during conversion

Data loss is one of the main concerns when migrating email archives. The tool fully preserves the following elements:

• Email. All messages (sender, recipients, subject, date, and body content (plain text and HTML)).
• Folder structure: The PST file will include the same hierarchy of your Inbox, Sent Items, Drafts, and any custom folders you defined in Outlook for Mac.
• Attachments. Any connected PDFs, pictures, spreadsheets, papers, and other materials are maintained and accessible.
• Calendar entries. Your Outlook for Mac calendar appointments, meetings, and events are imported.
• Metadata retains read/unread status, timestamps, and other email attributes.

You end up with a faithful replica of your Mac mailbox in a format that Outlook for Windows natively recognizes.

Large OLM Archives Tips

If you have years of email history, OLM files can be a few terabytes. Some practical tips for managing huge archives:

1. Before uploading, check the size of your file. If your OLM is too big, make sure you have a reliable internet connection. The most reliable upload will be over wired Ethernet or robust Wi-Fi.
2. If you need to. Export in batches. In Outlook for Mac, you may choose the folders to export. If your complete archive is quite enormous, you might choose to export smaller batches and convert each of those independently.
3. Make sure you have enough disk space. Ensure your Windows PC has enough free storage space to download the PST file. The size of the PST file will be around the same as the original OLM file.
4. Let the cloud do its thing. Because the program runs on our servers, your local machine’s specs and speed don’t impact the conversion. It runs the same on an outdated laptop as on a high-end desktop.

Summary

If you are migrating from Apple Mail, not Outlook for Mac, please visit our tutorial on converting OLM to PST instead. Let OLM to PST conversion not be a technological hassle for you. Outlook for Mac and Outlook for Windows have a well-known format difference, and the software addresses it simply. Upload your OLM archive, allow the cloud-based converter to work its magic, and then import the resulting PST file into Outlook on your Windows PC. Your emails, folders, attachments, and calendar entries all come in at once.