Next I created a new Gmail account, and used Gmvault to "restore" (shift) the email messages to the new account,
to simulate a migration. I aborted about 3 hours into the process, after becoming convinced the process works very
well (I didn't really want my email to migrate to a new account). Messages uploaded without a hitch and with their
original labels and other metadata perfectly intact--except for importance markers, which are not included in the
process. All in all, it was a stellar performance: Gmvault worked exactly as described, and with virtually zero
annoyances. The only problem I ran into was that the upload process severely congested my broadband connection,
making it very slow; but you could avoid that issue by running the restore process overnight (or over several
Gmvault is open-source, and the project accepts donations.