I've SP Calendar with enabled incoming email. If Security policy set to
Accept e-mail messages based on list permissions
and user who sends a meeting request has Contribute permissions - it doesn't work.
If Security policy set to
Accept e-mail messages from any sender
it does work.
Also if you have an Exchange account (which has the Email field as following:
SMTP:MyCal@MyDomain.com) and specify it - it also doesn't work. However I do have the same calender where the last approach work.
Can you clarify what is missed? I just need to create an event based on the permissions.