Most people are unaware that there is a drastic difference between Microsoft Outlook and the smaller Outlook Express. While the graphics for these two programs may be similar the actual function of them is completely different.
Microsoft Outlook uses an extremely proprietary file and message storage system. This is the PST file. The Outlook PST File is a hybrid of a conventional file and a database. As such all of the messages that come into the Outlook inbox are saved to the PST file. When PST recovery is performed, they are recovered from this same location. However, there are a few serious problems that occur when saving and attempting to reopen messages stored in this manner.