# Trigger help on mqtt

**URL:** <https://discourse.nodered.org/t/trigger-help-on-mqtt/8273>\
**Category:** General\
**Created:** [22 February 2019 13:28 UTC](https://discourse.nodered.org/t/trigger-help-on-mqtt/8273 "2019-02-22T13:28:20Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![moltenpiston](https://avatars.discourse-cdn.com/v4/letter/m/e36b37/32.png) [@moltenpiston](https://discourse.nodered.org/u/moltenpiston)\
**Post date:** [22 February 2019 13:28 UTC](https://discourse.nodered.org/t/trigger-help-on-mqtt/8273/1 "2019-02-22T13:28:20Z")

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Goodmorning everyone  
I have a mqtt input, which every 10 seconds tells me the status of a device (true or false). I would like to send an email only with each change of state, and not every time I receive a publisher. how can do ? thank you for your reply - Paolo

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**Author:** ![ukmoose](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/ukmoose/32/13_2.png) [@ukmoose](https://discourse.nodered.org/u/ukmoose)\
**Post date:** [22 February 2019 13:34 UTC](https://discourse.nodered.org/t/trigger-help-on-mqtt/8273/2 "2019-02-22T13:34:09Z")

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Take a look at the `RBE` node (report by exception).

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**Author:** ![moltenpiston](https://avatars.discourse-cdn.com/v4/letter/m/e36b37/32.png) [@moltenpiston](https://discourse.nodered.org/u/moltenpiston)\
**Post date:** [22 February 2019 13:46 UTC](https://discourse.nodered.org/t/trigger-help-on-mqtt/8273/3 "2019-02-22T13:46:45Z")

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thanks with RBE it's ok