Welcome to the forums,
Register in bugzilla then add a vote / tagged support ticket request to this RFE:
Bug 16472 - Support for local folders when syncing with Zimbra Server (there's also
Bug 14462 - Local Archiving)
-You can also CC yourself on it if you'd like to get email updates (ie: so you know when it's implemented).
Just to orient you a bit:
Bugs & RFE's (requests for enhancements) can be filed/voted for in
Bugzilla & tracked (see priorities & what release their going into) via
PMweb.
The
blog has lots of good articles - you might checkout:
Open Source Product Management: How do features get into Zimbra?
Last but definitely not least - the
Wiki has all sorts of collective knowledge in it
