I can't delete any events neither from Exchange Server nor from Outlook - I need them available on my Macs, IPhone, IPad, OutlookWebAccess.
What I did in between was to create a new identity and set up the accounts totally from scratch (only after I did a backup of the current identity) - after that, ALL calender events from Exchange showed the same 19126 error and not a single one of the approx 10.000 appointments was synchronized to Outlook! And all enets brought the error each time, outlook checked with the exchange server - can you imagine how many error messages I received?
After deleting the new identity and recovering the identity from the backup, I am back at 1 appointment with 19126 error.
In between I checked with Outlook 2010 for Windows and the appointment in question does not exist on the server! In Outlook 2011 for Mac I can't find it either, but the sync daemon in outlook 2011 for mac still complains, that he can't synchronize it - which I can fully understand, as it doesn't seem to exist neither on the local machine nor on the server.
It is inly one appointment, but I receive one error for it each time the client (Outlook for Mac 2011) checks with the Exchange Server for synchronization - every 30 seconds or so.
So I have no idea what to do :-(