I create a Calendar Event, I invite users, how do i find the email i

In outlook you have in your sent items an email with the calendar/
meeting with the users etc.
I have this problem with Office 2004 and 2008, when i setup Exchange
emails.
I had a problem where a person did not turn up to a meeting and I was
unable to prove that i sent the email to him.
is there anyway to check a receipt of what was sent out in the
calendar invite? I find that i have multiple changes and it is good to
have a trail of what was sent out at what time.
Thanks