This feature provides power users with an extra dose of speed. When live, it enables the CRC32 checking of each MSG file. This fancy terminology really means that MSG Viewer for Outlook automatically checks to see if each file has been converted – saving you time by not re-converting the same emails again.
If you wish to re-process MSG files (for instance, if you changed a preference), we recommend you leave this option disabled. This is because CRC32 only checks to see if the MSG file was already processed, and not the preferences that were enabled when it was processed.