Ajakibs wrote:

Thus, I am not sure that if I simply open the message - it will have
any impact to
the archivization date considered. If it was the case, it would mean
that Microsoft made
a big bug when elaborating such kind of archivization.

Opening a message doesn't update the modified date (I just tried it), but,
for example, viewing the options and scrolling the headers will cause
Outlook to ask if you want to save the message, even though no changes
occurred. Moving from one folder to another, in some cases, also updates
the modified date. You may want to read this:
http://support.microsoft.com/kb/295657/en-us
--
Brian Tillman