I'm not able to reproduce these problems in any of my test accounts in Outlook MAPI. When you say proposed appointment do you mean just the initial invite, or do you mean that an alternative time has been proposed already? I've tested initial and proposed both from the email message and from the appointment itself and in both cases I see the expected behavior kick off immediately.
Kyle Kerst
IT Coordinator
SmarterTools Inc.
www.smartertools.com