Kapacitor email alert trigger DBout and HTTPout

I configured basic email alert via chronograf.
The script contains dbout and http trigger as well .
Why is that ?

var data = stream
|eval(lambda: “usage_system”)

var trigger = data
.crit(lambda: “value” < crit)

> trigger
> |influxDBOut()
> .create()
> .database(outputDB)
> .retentionPolicy(outputRP)
> .measurement(outputMeasurement)
> .tag(‘alertName’, name)
> .tag(‘triggerType’, triggerType)
**> **
> trigger
> |httpOut(‘output’)

InfluxDBOut is configured so chronograph can have the alert history.
I am not sure what ism se case for httpout.