I have a user that when she receives appointments/calendar meetings from 2 other users on the same domain (not exchange but Google Apps hosted email for their own domain), the appointments show up as e-mails, not appointment items that they can Accept/Decline or setup reminders for.
The recipient having the problem is on Windows with Outlook.
The 2 senders who she can't receive appointments from, 1 is on Mac with Outlook, the other is on Windows with Outlook.
If I have the 2 users send their appointments to me at my personal e-mail which is on Exchange, with Outlook 2010, I can receive their appointments just fine.
And if I forward the appointments, from my personal Outlook, to the lady who receives them as e-mails, she receives my forwards as appointments.
So I'm not sure what can be causing this!?