It should be possible to inform the admin by mail if a key value like “percentage blocked” changes dramatically.
At the moment the admin has to actively monitor pi-hole’s statistics to recognize a changed behaviour of a network client. This can be inspected by either increasing number of total queries or queries per client or blocked queries, etc.
It should be possible to set warn and alarm limits for clients in general, specific clients and over all network key values. The admin should be informed, if one of the set limits is crossed by a client or over all.
To be comparable numbers have to be normalized by time interval and/or number of clients. An admin could set limits in relation to the “healthy” network or client numbers.
For the beginning an integration of the described feature for the values “total queries”, “queries blocked”, “percentage blocked” should be sufficient.