Some Info:

I want to send a query to an exchange server over OWA by Webdav to receive items that are not markt as 'synced'

I mark an item by setting the custom property synced to 'synOKE'
Then when I'm searching for that property the sql query stays the same so I don't have the problem that 1000 query's will be cached for 40 days.

The problem:

If there is a new appointment everything works fine because I can search for the synced property. But when you change the appointment in outlook the appointment sill has the synced set to synOKE.

Is there a way to include the value of 'synced' in an property that resets when the appointment has changed or is there a way to compare some other ID property to a custom property in a search.