Notify users about new questions posted in the category where they have previously answered

Hi, is it possible to implement a notification system whereby previous Answerers get an email notification about new Questions posted in a specific category? For example, let’s say this user “John” has previously answered a question in the “Technology” category. When a new question is posted in “Technology” category, John will get an email notification saying something like:

Hi John! Someone has posted a new question in “Technology”! As you have answered in “Technology” before, perhaps you would like to help answer this question?

I know this is probably a long shot, but if not — how about having email notifications sent to people who have answered before, when new questions are posted ?