Ramhound is correct. Here is how I get around it.
If I'm concerned about attendees forgetting, what I do is:
- Copy the meeting text into a new email.
- Copy over the subject line and add "Reminder"
- Copy over attendees
- Set a send delay.
The last step can be done easily in Outlook - go to the "Options" tab at the top, click "Delay delivery", and set your terms.
You could also buy an outside service that does auto reminders, but the above steps really only take 12 seconds if your hotkey use is good.