Script to notify by mail

Dear all,

Is it possible to have or to point me if it already exists.

I am searching for a script that monitors either:

Interfaces > wan (tx and rx)
Or
Firewall > connections > orig / repl

And if the one of the metrics goes above 1 Mbps, to send an email warning that the interface or a connection with the traffic x is current active.

Thank you all for your input.