Motion Detection: detect people standing still at your door rather than passersby

I would like to have the ability to filter out passersby from people that actually stand still for a prolonged amount of time in front of my door, or within the drawn area of interest. Due to the fact that my front door is positioned closely to a busy pavement, and I have no front yard, just a front door directly opening to the pavement, I get too many motion detection notifications. Hence it would help if I could filter out passersby. Maybe combining video recognition with the motion sensor? Or comparing motion data from a "quiet" moment to the current situation, especially when no motion is detected anymore, but presence is still detected. Because people standing at your door is more interesting than people simply walking by. *I had to rewrite my post, it did not cover my idea well enough the first time.