This one is possible. I would like to bring your attention to a solution called Alert Text Control:
This is a free solution from Support (One of mine actually).
It's main purpose is to insert CI Names on the dispatches for devices but it's mechanism might help with this requirement you have. I see a couple possibles:
1. Because it's inserting the CI Name, Maybe you can then filter this off in your ticketing system or exchange server?
2. Because it uses a stepped approach where it draws all the data into a single record before dispatching, maybe you can apply a filter to the single threshold that then dispatches this and filter off from there
3. The xml code for this solution is open for modification if needed (Not encrypted), so adding a filter on the gatherer and filtering off via that is also an option
(I think #2 would be easiest)
Check out the Forum topic on Alert Text Control and if it sounds like something you would like to look at, just reply to that topic asking for a copy and we will ship it off to you.