Thanks to http://semnaitik.wordpress.com/2013/06/17/how-to-safely-compress-an-oversized-pst-file/
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 cannot store more data than its size limit. Microsoft Outlook PST file is categorized in two parts on the basis of format: ANSI and Unicode PST file.
- 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 cannot 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.
Whenever a PST file of any format reaches or crosses its size limit, it cannot be opened or loaded anymore in Outlook or you cannot add any more data to it. An oversized PST file is always prone to corruption or it may become at any time. But before an oversized PST file gets corrupted if you reduce or compress its size, then the situation of corruption can be avoided. Other than compressing or reducing an oversized PST file, you can split or break the PST file into multiple smaller parts. Click here to know how to break or divide an oversized PST file into multiple parts. But if a PST file is already corrupted, then you cannot perform compression and splitting of a PST file. In such critical situation you must repair the corrupt PST file with the help of SCANPST.EXE or third-party PST Repair application. Click here to know how to deal with a corrupt PST file of Microsoft Outlook.
The size of an oversized PST file can be compressed by managing your mailbox items and by simply reducing the size of PST files.
How to manage Outlook Mailbox in MS Outlook 2010 (my current MS Outlook version)
1. Open your MS Outlook program.
2. Click on File tab > click on Cleanup Tools > click on Mailbox Cleanup.
3. “Mailbox Cleanup” window will appear.
- Click on View Mailbox Size to view the total size of your mailbox and any other individual folder.
- You may find older items of your mailbox by selecting Find items older than ** days. Enter any number between 1 and 999 and click on Find.
- You may find larger items of your mailbox by selecting Find items larger than ** kilobytes. Enter any number between 1 and 999 and click on Find.
- You can also click on AutoArchive to move old items to the archive file.
- You can check the size of your deleted items folder by clicking on View Deleted Items Size and you can empty it permanently by clicking on Empty.
- You can also check the size of your Conflicts folder by click on View Conflicts Size and you can deleted it by clicking on Delete.
4. Now click on Close to close “Mailbox Cleanup” window.
How to reduce the size of an oversized PST file of MS Outlook 2010 (mu current Outlook version)
1. Open your MS Outlook program.
2. Now delete any items from the mailbox that you do not want to keep.
3. Open the Folder List view. Click on the Folder List icon, which is shown on the bottom of Navigation pane window or simply press CTRL+6.
4. In the Navigation pane window, right-click the Deleted Items folder and click on Empty Folder.
5. Now click on the File tab > Account Settings > again click on Account Settings.
6. “Account Settings” window will appear. Click on Data Files tab.
7. Select the Outlook data file that you want to compact and click on Settings.
8. “Outlook Data File” window will open. Click on Compact Now.
Note: Do not exit your MS Outlook program after you compact the PST file.
These two methods are very helpful to reduce or compress an oversized PST file of MS Outlook. But it these methods are difficult to perform or if you are looking for some advanced solution, you can take help of SysInfoTools PST Compress and Compact software. The software is very safe and easy-to-use application that requires no extra technical knowledge. It safely compresses or compacts an oversized PST file without causing any damage or data loss. In only removes extra and unused space from PST files and maintains all the attachments while compressing the files. To know more about this software, please visit SysInfoTools’ website and download the free demo version of this software.