Designed to be used to send email to your Phone carriers email to text gateway to enable you to get text messges from hubitat.
But also can be used for any emailing as well.
It is actually installed as a device not an app,
It does need a server to gateway your email through like your isp, etc.
It will show up as a native notification device.
Create one device for every sendmail (email:to) endpoint that you want as a notification device.
Uses native telnet implementation on hubitat.
It is also hosted on package manager as well, recommend you get it from there if you can.