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How to split PST file during EML to PST conversion?

How to split PST file during EML to PST conversion?

When it comes to managing large amounts of data in Outlook, one common issue that users face is the size limitation of PST files. PST files, which store all the emails, attachments, and other data in Outlook, have a maximum size limit set by Microsoft. This can cause problems when trying to import a large number of EML files into Outlook.

The amount of data coming in from everywhere is growing all the time, and the Outlook PST file is no different. Lots of emails every day, lots of attachments, forwards and replies. However, the PST size is limited by Microsoft by default, so you may face the problem when Outlook stops working.

For example, Outlook 2002 PST file size is limited to 2 GB, Outlook 2003-2007 PST file size is limited to 20 GB. Modern versions of MS Outlook 2010 and above are limited to PST files of no more than 50 GB in size. But what if you need to import tons of EML files?

However, with the latest versions of Outlook Transfer products (5.2 and above), a new feature has been implemented to address this issue. Users now have the option to split the output PST file into smaller parts during the EML to PST conversion process. This allows for easier management of large amounts of data and ensures that the PST file size remains within the limits set by Microsoft.

Option - Split Output PST File and Volume Size

How to split PST file automatically:

We will review it on example of EML to Outlook Transfer tool…

  1. Run the EML to Outlook Transfer utility.
  2. Select the “Save to PST file” option from the “Mode” menu.
  3. Go to the “Options” menu and select “Split Output PST File“.
  4. Choose the desired size for each PST file part (volume).
  5. If desired, select the target Outlook folder from the “Options” menu.
  6. Specify or select the source folder where the EML files and folders are stored.
  7. Click the “Scan Folder” button to scan the nested subfolders.
  8. Finally, click the “Save PST” button to start the EML to PST conversion.

During the conversion process, the Outlook Transfer tool will write all the imported data into several PST files, with each part numbered in the file name. These PST files can be opened separately in Microsoft Outlook by going to the “File” menu, selecting “Open”, and then choosing “Open Outlook Data File…”.

How to split PST file manually

In addition to the PST splitting feature, the Outlook Transfer Tool also offers the ability to save and load the email container list. This functionality allows users to pause the data conversion process and resume from the same point, but specify the new PST file name for output, which can be useful when working with large data arrays.

  1. Run the Outlook Transfer software.
  2. Specify the source folder and click the “Scan Folder” button.
    This will populate the list of email containers. Each source file will be selected by default.
  3. Go to the “Edit” menu and use the “Deselect All” option.
  4. Select the first part of the source files (you can do this by holding down the Shift key and moving the selection with the Down/Up keys).
  5. When you are done, go to the “Edit” menu and use the “Check Selected” option.
  6. Now click the “Save PST” button and convert the first part of the emails.
  7. Do the same for the second and other parts of the source, specifying the new PST file name each time.


Overall, the ability to split the PST file during the EML to PST conversion process provides users with a convenient way to manage and organize their data in Outlook. It ensures that the PST file size remains within the limits set by Microsoft and allows for easier navigation and access to the imported data.

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I face the problem that I need to transfer a huge *.box file [65 GB – ca. 190k items] into a *.pst file. The above explained way for splitting does not work.

Any recommendations?

This article describes PST splitting during the EML to PST conversion. It is not about the BOX splitting. Please contact our support team with that question, they will be happy to assist.

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How to split PST file during EML to PST conversion?

time to read: 3 min