I used the ZCS Import Wizard for Outlook to import users .pst files - all calendar appointments are now meeting requests instead - and read only. I tested Kerio awhile back and ran into same problem there - something to do with the originator of the appointment not matching up

I guess I'm going to have to manually copy all appointments to Zimbra - no easy task for a couple of my users that have tons of them & booked into the next year.