A Unicode PST (Outlook 2003 and 2007 default PST) supports features like large file size and support for various character set. The Support for different character set gives flexibility over language control,Unicode vs ANSI PST and File Size Issues Articles while the latter one is somewhat more important. The increased file size limitation in Unicode PST is for users who cannot keep a regular track of errors and issues occurring due to 2 GB file size limitation that is imposed by an ANSI (American National Standards Institute) PST. Also, an ANSI PST that goes over 2 GB in size is vulnerable to corruption risks and various issues that ask to Split PST File. That’s the reason why most of the Outlook users prefer migrating to this new format of Outlook 2003 and 2007.

Outlook 2003 PST

The accounts of IMAP (Internet Message Access Protocol) and like Hotmail or MSN in Outlook 2003 still require an ANSI formatted PST, however the default is always a Unicode. So, issues related to PST file size depend on the account in use.

Note: You cannot convert an ANSI PST directly to Unicode or vice-versa. To do this, you need to copy, move or export the data to the new data file.

PST File Size Issues

The size related problems of ANSI formatted PST have already been depicted. A Unicode PST also faces such issues, though not similar. No doubt, a Unicode PST is the best solution in an enterprise environment as it resolves many issues that otherwise can force to spread the data across multiple PSTs. But simultaneously, it raises other problems like:

(1) User experiences poor performance when accessing a http://www.preetiunicode.com large PST . A PST till 2 GB provides good user experience, while the one between 2 GB and 4 GB is strictly dependent on hardware. A PST above 4 GB shows short pauses and the frequency of these pauses increases when the file goes above 10 GB.

(2) Considerable requirement of time when restoring from a backup of such PST.

(3) Management issues.


Storing the PST data in different PSTs, rather focusing on a single is a good practice to avoid the issues. So, you should keep on deleting the undesired messages from a PST and compacting it later. Also, you can opt solutions like PST archiving or using a commercial tool to Split PST. There are various tools available that can Split PST File and keep its size under control.

Stellar Phoenix PST File Splitter is an advanced utility that can split a large PST into smaller, Outlook-usable PST files. The tool can Split PST for MS Outlook 2007, 2003, 2002, and 2000. The software provides two criteria to split the PST file: by e-mail ID and by date.