When someone sends me an invitation for an event that happened in the past, Outlook will instantly pop up a reminder on my desktop, even though I haven't even opened the mail about the event yet.
How can I prevent Outlook from opening these reminders for events I'm not attending?
You can turn this off, in File -> Options -> Mail -> Tracking, uncheck the
Automatically process meeting requests and responses to meeting requests and polls
This feature is designed for a reason though, it is so people can see you have tentative appointments to reduce/prevent double bookings.
I do not know how you can achieve this based upon the time of the event (although you don't explicitly ask for it, although I suspect it would be helpful), my best guess is VBa
There is a caveat I just read
Even though a meeting request will no longer be automatically added as Tentative to your Calendar upon receiving, it will still be added as Tentative as soon as you select the meeting request in your message list.
