Add a Database, in a separate project ?
Create a Method to Compare 2 Events => same/not same/urgent (not wait).
Create an API to filter urgent/not urgents events.
Create a Policy logic:
- day/night hours with offline days: collect, release
- online days and hours: wait n hours, collect, release
Release will aggregate and collect all Events in a same mail.
Never reduce, only collect+release, risk of loose some important datas.
If same: just list the iterations with dates.