As an admin I want to know if my mailserver is an open relay
Being an open relay means that your mail server can be used by anybody else to send messages to others. Historically this was common and even the default configuration of open-source mail servers. Now days it means that your mail server will be abused for spamming and will suffer a very low reputation.
Therefore we should check if the local ip or domain is acting as an open relay and notify the administrator in case it is, so that they can change this and protect the reputation of their network.
This should be a simple test to perform, see eg https://goping.net/en/mailrelay. This may require a centralized lightmeter service.