1. Backup your Outlook data file(s). So long as you backup your data files you will be protected from any unwanted changes which may occur during editing or archiving operations.
2. Open Outlook and elect Work Offline (File | Work Offline).
3. Run ArchiveAssist to edit the Modified Dates as desired.
4. With the Modified Dates now set as you specified, run Outlook's Archive tool (File | Archive) to
archive messages according to your criteria. This step is optional; you don't have to create an archive now
for this procedure to take effect.
5. Use Outlook's Send/Receive tool to synchronize folders.
6. Close Outlook.
7. Open Outlook in Connected mode; the Modified Dates will properly reflect the changes you made with ArchiveAssist.