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How to Split PST File to Manage Outlook Mailbox

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By: semnaitik

June 2, 2018

An oversized PST file creates troubles for Microsoft Outlook users. Not only does it affect Outlook's performance, but it also leads to corruption. To handle an oversized PST file, you can break it into two or more parts. In this article, I'll show you how to split PST files to manage an Outlook mailbox.

Being an Outlook user, you must be aware of the PST file size limit. PST, aka personal storage table, is an Outlook data file created on the local system. It stores email messages along with their attachments, contacts, calendars, tasks, notes, journals, and much more. A large amount of mailbox content increases the size of your PST file and makes it oversized. Since Outlook data file has a size limitation issue, an oversized file is prone to corruption. How?

Microsoft Outlook uses two formats to save PST files: ANSI and Unicode. The ANSI format is used by the older Outlook versions like 2002 and earlier. On the other hand, the Unicode format is used by Outlook 2003 and later versions. Though both of these PST file formats are associated with Microsoft Outlook, they have different size limitations. ANSI PST files can reach up to 2 GB, while Unicode PST files can reach up to 20 GB or 50 GB. If you're using Microsoft Outlook 2002 or any earlier version, the Outlook data file can only store up to 2 GB of mailbox content. Whenever the file reaches its maximum size limit, it starts affecting Outlook's performance. And when the file crosses the size limit, it becomes prone to corruption. The same rule applies to a Unicode PST file. Although the Unicode PST file format gives you more storage space, it may also become corrupt.

Why Does the PST File Size Grow?

Being a personal storage table, the PST file stores all your mailbox content. If you regularly use the Outlook client, you're likely to receive hundreds or thousands of email messages each and every day. Sometimes, it may happen that the email messages you receive include big attachments. Such a large mailbox needs enough storage space to be stored. And this is the main reason why the PST file size grows day by day.

To handle an oversized PST file, you must split it into two or more parts. Also, you can compress the PST file size manually and/or remove duplicate items from the Outlook data file. But if you notice that the PST file is already corrupt, then there's no option left other than repairing it. Microsoft provides you with the Inbox Repair tool, aka the scanpst.exe utility, to repair the PST file. And if the PST file is not corrupt but it's near the maximum size limit, you must do what's necessary.

Split PST File into Smaller Parts

To prevent file corruption and other performance issues, you can split the PST file into two or more parts. Maybe now you're wondering "how to split a PST file." There are many vendors in the market which provide you with a PST Splitter tool to get this task done effortlessly. Although all such tools are available with the free demo, you have to pay for the licensed version. And if you're looking for a free solution, you may use some built-in features of the Microsoft Outlook client. Though they don't help you split PST files, you can import mailbox content from one PST file to another one. The features which you can use here are ArchiveImport & ExportMove to Folders, and Drag & Drop.

Before you can use any of these features, you need to create two or more new files, into which you can import the mailbox content from the main PST file. For example, you have a Unicode PST file whose size is 20 GB. You can split this PST file into 2 or 4 parts. If you want to split a PST file into two parts, you need to create 2 new PST files. And then you can import the mailbox content from the main PST file to PST File#1 and then PST File #2. There's no need to use any third-party tools in this procedure. Refer to this article for complete information: Split PST File into Multiple Parts – Try a Few Easy Manual Tricks.


The manual tricks shared in the above article are easy and effective just like a professional solution. But unlike a third-party PST splitter tool, manual tricks are absolutely free. Although it may take some time to use the manual tricks, you should always use them over a professional solution. I don't guarantee that the manual tricks will surely work for you, but there's no harm in trying them. But before you can try any of the manual tricks; don't forget to make a backup of the original PST file.
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