Why don't I see the event I got emailed about in the Event Monitor?

If you receive an email about an event, but it doesn't appear in the Event Monitor, it's probable that the event has expired because the problem is no longer occurring. In order to see problems that occurred in the past, but may not be occurring now, you need to also view the expired events by unchecking the "Open Events" option.

The "Open Events" view is a list of active problems: each event is given an expiration time when it is created which usually coincides with the next time this problem will be checked. When the old event expires, if the problem has been fixed a new event will not be created, and it will no longer be visible.