Making sure that all e-mail-related services are working correctly is something that each hosting company and intranet administrator needs to perform on a daily basis. In order to do this, Nagios can watch these servers and make sure things are working as expected. This can be done by a remote machine to make sure that the services are accessible, or can be monitored by the same server that offers these services.
Nagios can make sure that the processes are running and waiting for connections. It is also easy to verify whether a predefined user and password pair is working properly to make sure that a custom authorization system is working properly.
This section describes the commands that check e-mail servers using network connectivity. The plugins that verify specific processes on a server can be used to make sure a particular daemon is up and running as well.