I have just found that this was an old bug of office (SP1)
http://support.microsoft.com/?scid=k...6253&x=16&y=16
This
" You receive the following error message:
You cannot respond to a meeting without an organizer. You must add an organizer field to the item.
Additionally, if you click the Scheduling tab, the e-mail alias for the organizer is replaced with either your e-mail alias or the e-mail alias of another attendee."
is exactly what is happening to me!
But why does it happen and how to fix it?
We have Windows XP with automatic updates active and Office 2003 SP2.
We did not change anything in the windows/Office config except deinstall the odl 4.0.3 ZimbraOutlookConnector and install the new 4.5.1 ZimbraOutlookConnector.