Do you utilize resources in Zimbra. We have our meeting rooms setup as resources and when someone adds a calendar entry to the resource and invites attendees it sends the invite out from the resource and when you try to send a response back it gets this error as well. The solution is instead of adding the calendar entry in the resources calendar the user needs to add the event in there calendar and invite the resource and it will auto accept if you have set it up to do so. The user then becomes the event organizer and people can respond to the messages and the calendar event still gets booked to the resource.
This might not be the problem for you but hope this helps. |