Thats gives you a free cloud based NodeRed server instance and you can set up an http enpoint which an ESP can send data to and then have a Node Red flow that does things with the data like sending emails. There is a little learning curve to learn about NodeRed but its really quite easy.
As an example, here's one i have where an ESP sends in soil moisture readings from a hygrometer sensor and the NodeRed flow looks at the value and if the soil is getting dry it sends a tweet saying it needs watering or if it doesn't get a reading in 24 hours it sends an email saying somethings happened to the sensor (flat battery?). This was easy to do with NodeRed but would have been a lot of work to write and test ESP code to do: