A description of data storage problems with non-Unicode PST files in MS Outlook, as well as features in Outlook Import Wizard to receive after convert Unicode PST (Personal Folders file) files.
Sooner or later, users of obsolete versions of MS Outlook encounter the deficiencies of the data storage format used in Personal Folders files in Outlook 97-2002. The old format, also known as ANSI PST, has a limitation on the number of elements (messages) in each directory of 65,000 (or 16,000, if the .pst file was created by an older version of Outlook), and the overall PST size may not exceed 2 GB. Beginning with the 2003 version, Outlook has a new file format for storing messages and personal data, which is most often referred to as Unicode PST. It supports the Unicode character standard and does not have limitations on the number of directory elements or PST size.
The main problem when migrating to modern versions of MS Outlook is that there are no automatic methods to convert ANSI PST files into Unicode. The simplest means to convert Unicode PST-noncompliant files is to create PST file mailboxes with Unicode PST support and to then import information from old data files into them. If for some reason you are unable to make use of MS Outlook’s built-in functions for this task (for example, you only have a backup copy of individual .msg messages available), then the best tool for e-mail message migration is Outlook Import Wizard, a convenient and reliable PST tool.
You can use Outlook Import Wizard to create PST file mailboxes (in “Create new PST file” mode) and import into them MSG files or transfer e-mails into a default PST file. In this case, your PC must have Outlook 2003/2007 installed, and a new Unicode PST file is created automatically when MS Outlook is first launched. The support for Unicode by Outlook Import Wizard is without compare, so you can be sure that the catalog names and meta-data for your e-mail messages (sender/recipient names, data and time of sending/receipt, message subjects, etc.) will be correctly transferred to the Unicode PST file.
When set to update an existing PST file, Outlook Import Wizard supports working both with old ANSI .pst files, used by MS Outlook 97-2002, and new Unicode PST files in MS Outlook 2003 and 2007. In light of the expected new version of Microsoft Office, it is also planned to add support for Outlook 2010 to Outlook Import Wizard.