Summary: Outlook creates different data files to store a copy of mail items locally on the system based on the OS platform and email server. Outlook users on Windows can export their mail items using Import Export wizard to PST format for backup and migration purposes. Similarly, Outlook for Mac users exports their data to OLM format for backup and transfer of data from one profile to another on the Mac computers. In this blog, we have discussed the differences between the two Outlook data files and recommended methods to convert and migrate mail items from Outlook for Mac (OLM) to Windows.
Contents
Microsoft Outlook is a business email client popularly used to access Outlook.com, Office 365, and Exchange accounts. Outlook client is available for Windows, macOS, Android, and iOS. On Windows, Outlook creates either OST (Offline Storage Table) or PST (Personal Storage Table) file based on the email server to store the mail items, such as emails, attachments, contacts, notes, calendar items, etc.
On Mac computers, Outlook stores the mail items in an OLK file format (.olk14Message and olk14MsgSource). However, you can export the mail items from OLK file format to OLM (Outlook for Mac) file format using the import and export option in Outlook on macOS.
Both OLM and PST file formats are used to backup and migrate Outlook data from one Outlook profile or computer to another. However, OLM and PST are two completely different Outlook data file formats.
In this blog, we explain the difference between OLM and PST Outlook data file formats and their usage in various scenarios, such as mailbox backup and migration.
Outlook for Mac (OLM)
OLM or Outlook for Mac file format is solely supported by Outlook for Mac. Outlook for Mac users use the OLM file format to back up and move their mailbox data between Outlook for Mac installs on different Mac systems. You can export or import the OLM file using the Import and Export options available in Outlook for Mac.
Figure 1: Outlook for Mac Import Export options
But the imported data in Outlook for Mac is stored locally and does not sync with the server.
Also, while exporting the OLM file, you can select the item types but can?t select the specific mailbox items or accounts. Thus, if your Outlook for Mac has multiple profiles, the export option exports the data from all accounts set up in Outlook for Mac.
Figure 2: Exporting OLM in Outlook for Mac
Unlike PST, you cannot import an OLM file to your profile on Outlook for Windows, Office 365, or Live Exchange Server. Thus, OLM is not a recommended way to transfer or migrate data between devices.
However, you can convert the OLM file to Outlook importable PST format using a third-party OLM to PST converter tool, such as Stellar Converter for OLM.
The software converts the Outlook for Mac (OLM) file to PST format with complete integrity and consistency. In addition, it allows you to choose specific mail items from multiple accounts after scanning OLM and lets you save them in individual PST files.
Figure 3: Preview OLM Mail Items
Besides PST, you can also export the mail items from OLM to PDF, HTML, and RTF formats or export the OLM directly to Office365.
Figure 4: Export OLM to PST
You may also append the data from the converted OLM file to an existing PST file.
Figure 5: Export OLM data to new or existing PST file
Personal Storage Table (PST)
PST or Personal Folder is a portable file format supported by both Outlook for Mac and Outlook for Windows. It is the most commonly used Outlook data file to store, backup, and migrate mailbox data from one Outlook profile to another on Windows or Mac.
Figure 6: Outlook Import Export Wizard
Microsoft Exchange Server and Offiec365 also support PST files. You can use Outlook on Windows to export mail items, such as emails, contacts, attachments, etc., to PST format using the Outlook Import Export wizard. Similarly, you can import the PST file to any Outlook profile using the Outlook Import Export wizard. The imported data from the PST is stored locally and synced with the mailbox on the server.
Figure 7: Exporting Outlook Data in PST File
You can also open and access the mail items from a PST file directly in Outlook without importing the file to your Outlook profile.
Figure 8: Open Outlook PST file in Outlook
Outlook users can move their old mail items from their Outlook profile to a local PST file to reduce the Outlook data file size and free up the storage space on your mail server. In addition, this helps you fix the send receive errors in Outlook that may occur when you reach the maximum mailbox quota limit assigned by the administrator.
Figure 9: Archiving Outlook data to local PST File
You can also copy a PST file to any location and import it to your Outlook for Mac account to transfer Outlook data from Windows to Mac with 100% consistency.
Figure 10: Importing PST in Outlook for Mac
Difference Between OLM vs. PST
Below we have summarized the differences between OLM and PST files,
| OLM | PST |
| OLM is an Outlook for Mac data file. | PST is an Outlook data file supported by both Outlook for Windows and Mac. |
| Used to backup and migrate mailbox items, such as emails, contacts, attachments, etc., from one Outlook for Mac to another. | Also, used for backup and migration of mail items from one Outlook profile to another on Windows and Mac systems. |
| Outlook does not create OLM files for Mac by default. | Outlook creates PST to store POP3 email items by default. |
| You can export or import OLM files solely in Outlook for Mac. | You can import the PST in both Outlook for Windows and Mac. |
| Outlook for Mac exports all account data into a single OLM file. | Users can choose specific accounts, mail folders, and items during PST export in Outlook Import Export Wizard on Windows. |
| Imported OLM file data is stored locally and not synched with the server. | Imported data to the Outlook profile is stored locally and synchronized with the mailbox on the server. |
To Wrap Up
OLM and PST files are widely used to backup and migrate Outlook mail items in Outlook for Mac and Outlook for Windows, respectively. PST is a portable file format, which can be imported to Outlook for Windows, Outlook or Mac, Exchange Server, and Office 365. Whereas OLM can be imported to Outlook for Mac profiles only. Moreover, you don?t get many options while exporting Outlook for Mac data to OLM files, which prevents you from exporting or importing specific mail items or accounts data. The recommended way to transfer Outlook for Mac data is by using an OLM to PST converter software, as discussed in this blog. The software can help you quickly convert and export mail items from OLM files to PST and other file formats. You can select specific accounts or mail items and export them to PST or Office 365. You can download Stellar Converter for OLM for free and evaluate yourself.
