Only tell them when the network path changes.
Alerts › rules. Kinds sit under the tags. Network path is one tick. None ticked still means every kind.
Tick network path
Open Alerts › rules and press + rule. Under kinds, tick network path and leave the others clear. That kind is a new external IP or a WAN failover. None ticked still means every kind. The address is typed and not added yet. Type and tags left empty cover every machine.
Read the sentence, then add the rule
Press add contact. The grey sentence reads: tell email ops@example.com when a warning or worse (network path) opens on 6 machines in Example Co, and again when it resolves. Press add rule when that sentence is the one you want. This shot stops before that. A later edit of the same rule is Change an alert rule.
A rule for every kind is Tell someone when a machine needs attention. Disk only is Only tell them about disk alerts. Downtime only is Only tell them about downtime. A Docker app is Only tell them about a Docker app. A failing check is Only tell them about a failing check. A reboot is Only tell them about a reboot. A custom metric is Only tell them about a custom metric. What the machine reported is on its overview: See when the external address changed. A script that starts on that change is Run a script only when the network path changes.