MS Outlook Versions: Microsoft Outlook has two versions, previous Outlook versions has ANSI format and support MS Outlook 2000 and 2002/XP, which have maximum file size limit of 2 GB (ANSI PST). Outlook Later Version is in Unicode format and supports Outlook version 2003 and 2007.
Possible Reason for Converting Unicode to ANSI: If you have some Outlook PST file of newer Outlook versions 2003 or 2007; but, you don’t have that version 2003 or 2007 to open that file. Now, this creates a need to degrade Unicode to ANSI. So, in place of investing in a costlier Outlook version, you can opt a cheaper way to solve your problem by getting a software to convert Outlook PST file from Unicode to ANSI which you can open in the older Outlook version (97/2000/2002) existing on your system.
Tool to Open New Outlook Version in Earlier Outlook Version: To open Outlook 2003 in earlier Outlook version you need to use some reliable third-party tool. There are several outside tools available in the online market you need to opt for some apt tool for this purpose using which you can easily open Outlook 2003 in earlier Outlook version. It is better to use some result-oriented software package for this purpose.
One third–party tool on which you can rely is PST Upgrade software, which is easy-to-use to open earlier version PST in Outlook 2007. Using this tool you can easily and quickly solve your problem in the best possible way. With the help of this proficient tool you can open Outlook 2007 in earlier Outlook version. The tool is competent enough to open earlier version PST in Outlook 2003. Using this tool you can also open PST Outlook 2007 in earlier Outlook version i.e. from Unicode to ANSI PST.