Nagios: How to aggregate a large amount of notifications into one email notifcation

I always look at these warings this way. If one is new to Nagios, then Nagios is suggesting something may not be quite right and maybe you should look at it. Once yo uknow what you are doing, ignoring these warnings is an informed decision. If it works for you, stick with it.

Something must be misconfigured somewhere, or the host is coming up quicker than the service checks failing. Even in the URL that Khaled posted it says host checks are done on-demand when a service changes state:

Hosts are checked by the Nagios daemon:

• At regular intervals, as defined by the check_interval and retry_interval options in your host definitions.
• On-demand when a service associated with the host changes state.
• On-demand as needed as part of the host reachability logic.
• On-demand as needed for predictive host dependency checks.

This basically says that Nagios will check on set intervals, and when a service changes state. When a service breaks (goes into a WARNING/CRITICAL state), a host check is executed, and if the host is seen as down, it should suppress the service notifications, assuming you have it configured that way. Can you show us your service and host definitions, masking any hostname/addresses to protect the innocent if you want.

As a side note, I've been using Nagios for years, and never had a service alert when a host is in a down state, unless I specifically configured it to do so.