I'm working on integrating Exchange with an existing application. Basically, the existing application schedules meetings, so this would be quite beneficial as users would be able to track them in Outlook. Tying the current system into Exchange to create the Appointments was pretty simple. For a bit of background, we're using a master account to be the "owner" of all meetings as we don't have everyone's Exchange credentials, so everything will be done via this single account.

I've set up a folder sync action on the inbox of the master account. I can snag all emails (which should only be meeting responses) and process them. However, we're attaching extended properties to the Appointment objects to help tie them into our existing application. These extended properties are going into the Appointment object just fine. They show up in the Meeting Request in the inboxes of the attendees. They even wind up attached to the Appointment in the attendees' calendars. However, they are NOT present in the Meeting Response when the user replies with Accept, Decline, etc, which adds some extra muckery that I'd like to avoid. I've tried this with standard email messages and extended properties are lost on the reply there as well.

Is there any way to preserve extended properties throughout a conversation? Perhaps a flag to set on the object? I'd really like to see these on the Meeting Response objects if at all possible...

Then again, this wouldn't be an issue if I could just get all of the necessary information from the Appointment object, but for that, I'd need to dig data out of the PR_MESSAGE_RECIPIENTS table (Largely new time proposals) attached to it, and that appears to be flat-out impossible with the managed API.