To determine your Personal Folders file (.pst) format, do the following:
1. On the Tools menu, click Options.
2. Click Mail Setup, and then click Data Files.
3. Click the data file you want to check, and then click Settings.
4. Check the Format field to see if it contains the string Personal Folders file or Personal Folders file (97-2002, only 2GB). Personal Folders file indicates the new format that supports multilingual Unicode data and offers greater storage capacity (20GB) for items and folders.