Bob Schwartz diznbird at em ess en dot com wrote:

Nothing got carried over, but I solved the problem last night. All
the old folders had apparently been automatically archived as .pst
files during the installation process.

While PSTs are used for archiving, they're also used for every other item
data store as well (except for Exchange mailboxes) and so those PSTs, or at
least one of them, was in use as your active message store in the prior
version. Installing a new version does not automatically archive anything
and, while it may create one additonal PST, it does not touch your prior
message stores in any way.
--
Brian Tillman