mqttwarn subscribes to any number of MQTT topics (which may include wildcards)
and publishes received payloads to one or more notification services, including
support for notifying more than one distinct service for the same message.

For example, you may wish to notify via e-mail and to Pushover of an alarm
published as text to the MQTT topic home/monitoring/+.

WWW: https://github.com/jpmens/mqttwarn