As described in the release notes:
https://github.com/OpenSprinkler/OpenSprinkler-Firmware/releases
“The event when a master zone is turned on has been added to MQTT, IFTTT, and Email notifications.”
Currently it does NOT send notification when master is turned off. There are two reasons: 1) this is added mainly to address some customer’s requests that they want the ‘master on’ event to be sent on MQTT in order to trigger other actions; the ‘master off’ event doesn’t matter; 2) it was easy to change the firmware to add support for ‘master on’ event while ‘master off’ requires significant more changes. This is mainly because the way master zones are implemented are different from regular zones, and unlike regular zones, master zones don’t appear in the running queue, nor do they have scheduled duration, their on or off status is completely determined on the fly by other zones’ statuses. For that reason, we didn’t add ‘master off’ but this can be added in the future.