If you are sending notifications with DFM, you need to only check the boxes for events in your Notification Group config. If you check the alert boxes, then you will get notifications containing the alert summary. The events are the atomic device problems, and contain much more useful information.
By default, DFM will age out cleared alerts and events every month. You can configure the time of day at which the purge job runs, but you cannot change the number of retention days. The purge time can be configured under DFM > Configuration > Other Configurations > Daily Purging Schedule.
