Safe and Secure Blackberry Unlocking
Secure Blackberry Unlocking
If I delete a calendar invite, instead of accepting or declining it, the meeting will go on my calendar marked tentative. I consider this a safety feature, since it keeps you from losing the meeting info if you accidentally delete it. Declining the meeting will cause it to not be put on the calendar.
I'm on BES, if you're on BIS or not using Outlook, your results may be different.