Safely Compact PST File using Outlook Compact Feature

compact pstOutlook users are primarily concerned about the size limitation issue of PST files. If PST is in ANSI format, you can’t store more than 2 GB data. On the other hand, Unicode PST can store up to 20 to 50 GB data. If your PST file is large in size, it may cause performance issues. But if it exceeds the size limit, it leads to corruption. In such situation, you can try Outlook Compact feature that can compact PST file without causing any changes.

PST or Personal Storage Table file is an Outlook data file that stores all your Outlook mailbox items, such as email messages, contacts, calendars, appointments, tasks, distribution list, etc. The size of your MS Outlook mailbox grows by creating and receiving items. When you delete some of the items from your Outlook Mailbox, its size might not decrease. All the deleted items go to the Deleted Items folder, and by this way, they are still present in the file. An Outlook PST file has a size limit, which means it can’t store more data than its size limit.

Types of PST Formats

Microsoft Outlook PST file is categorized in two parts on the basis of the format:

ANSI PST File: An ANSI PST file is used in older versions of MS Outlook (97 to 2002) and this format is restricted to US English. The characters of other languages need to be encoded in this format; otherwise, those characters cannot be shown. This file format has a size limit of 2 GB, which means it can’t store more than 2 GB of data. The size limit of ANSI PST file cannot be increased.

Unicode PST File: A Unicode PST file is used in the newer and higher versions of MS Outlook (2003-2013) and this format can represent most alphabets on your computers. The file format has a size limit of 20 GB to 50 GB, i.e. 20 GB in Outlook 2003 & 2007 and 50 GB in Outlook 2010. The size of a Unicode PST file is fairly enough to store a large amount of data.

PST Size Limit Issue

Whenever a PST file, be it ANSI or Unicode, reaches or crosses its size limit, it starts causing serious troubles for Outlook users. Neither you can open the file, nor can you add more data into it. An oversized PST file is always prone to corruption. Also, it causes serious performance issues which definitely annoy Outlook users. To avoid all such unwanted but painful situations, you can compact PST file by reducing its size. We’ll discuss how to do that in this post later. Also, you can break or split PST file into multiple smaller parts to avoid corruption due to size limitation problem. Read this blog post to know the Easy Way to Split PST File into Multiple Smaller Parts.

There’s one more thing you can try here. A PST file may have numerous duplicate items which occupy enough space. You can remove them in order to get enough free space in PST files. Read this blog post to know the Smart Way to Remove Outlook Duplicates with Ease.

Corrupt PST File

But if you have a corrupt PST file, then you can neither compress PST file nor can you split PST it. In such a critical situation, you must repair PST file with the help of scanpst.exe or any third-party PST Repair application. Read this blog post to know how to Repair PST File by using Inbox Repair Tool (scanpst.exe).

Outlook client has a wide range of smart features including compacting PST file. The Outlook Compact feature can safely compact PST file by removing all the unused extra space. Remember you won’t gain space automatically when you deleted items from the PST files. You must compact PST file to get enough free space. Before you can compact PST file, first you should manage your mailbox items and then you can reduce PST file size. Below steps show you how to manage Outlook mailbox.

Four Steps to Manage Outlook Mailbox

Step 1: Open your Microsoft Outlook program.

MS Outlook-2010

Step 2: First click File tab on the taskbar. Then click Cleanup Tools > Mailbox Cleanup.

mailbox cleanup in Outlook 2010

Step 3: The Mailbox Cleanup window will appear.

mailbox cleanup (2) in Outlook 2010

Click View Mailbox Size… to view the total size of your mailbox and any other individual folder.

mailbox folder size in Outlook 2010

Click Close.

You may find older items of your mailbox by selecting Find items older than ** days. Or also, you may find larger items of your mailbox by selecting Find items larger than ** kilobytes.

advanced find in Outlook 2010

Enter any number between 1 and 999 and click Find Now.

  • To move old items to the archive file, you can also click AutoArchive.
  • You can check the size of your deleted items folder by clicking View Deleted Items Size and you can empty it permanently by clicking Empty.
  • You can also check the size of your Conflicts folder by click View Conflicts Size and you can delete it by clicking Delete.

Step 4: Now click Close to close the Mailbox Cleanup window.

Compact PST File using a Simple Manual Trick

Step 1: Open Microsoft Outlook program, and delete any items from the mailbox that you don’t want to keep.

Step 2: Open the Folder List view. Click the Folder List icon shown at the bottom of the Navigation pane window or simply press CTRL+6.

Step 3: In the Navigation pane window, right-click the Deleted Items folder. And then click Empty Folder.

Step 4: Now click File tab > Info > Account Settings…

PST compact in Outlook 2010

Step 5: The Account Settings window will appear. Click Data Files tab, and select the Outlook data file.

PST compact in Outlook 2010

Now click Settings.

Step 6: On the Outlook Data File window, click Compact Now button to compact PST file.

PST compact in Outlook 2010

Step 7: Please wait until the compact process gets successfully completed.

PST compact in Outlook 2010

Important note: Don’t exit Microsoft Outlook program after you compact PST file.

Professional Way to Compact PST File

These two methods are very helpful to compact PST file of Microsoft Outlook. But if you’re looking for a professional solution to avoid all these manual steps and achieve best results, you should try PST Compress and Compact tool provided by SysInfoTools Software. It’s very safe and easy-to-use application that requires no extra technical knowledge. It can compact PST file of any size without causing any damage or data loss. It only removes all the extra and unused space from PST files and maintains all the attachments while compressing PST files.

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