Q: How is it determined if a calendar update should be made?
A: Here are the steps on how to see if any items in a Calendar have been rebased. This should be done only on any items that the user is the organizer for.
1. Open MFCMapi (aka: MAPIEditor)
2. Expand the store that you are interested in. (This will assume a Mailbox store.)
3. Open Root Container, Top of Information Store, and then open the Calendar to display the list of items.
4. Click on an appointment to display its properties.
5. Scroll to the right of the Properties window and then click on Named Prop Name to sort by that column.
6. Look for:
0x825E (timezone that was used when picking start time)
0x825F (timezone that was used when picking end time)
If those properties are there on a single instance item then you can be sure that the appointment was rebased.
Stephen Griffin has detailed information on these MAPI props here: http://blogs.msdn.com/stephen_griffin/archive/2006/12/06/outlook-2007-timezone-structures.aspx