Please let me know if anyone can reproduce this:
If a Zimbra user using Outlook '03 with Zimbra Connector 6.0.2 schedules an appointment and invites attendees with Exchange mailboxes, the tracking records for that appointment for the exchange attendees will not be updated with their responses (accepted, tentative, decline, etc...)
How to reproduce:
From Outlook 2003 w/ ZCO: Create an appointment
Invite a user with a Zimbra Mailbox
Invite a user with an Exchange Mailbox
Instruct both users to "Accept" your meeting invitation, and send a notification email
Open the appointment
Click the Tracking tab
Under the Response column observe:
For the Zimbra attendee, the response will be "Accepted"
For the Exchange attendee, the response will be "None"
I also filed a bugzilla on this one: