I was an Iris user and just got my Smartthings V3 hub. My Iris hub used to send me an email when the hub goes offline. I try to setup something similar with my new Smartthings V3 hub but I can’t get it to send me anything (email, notification, SMS, or etc). I did turned on the “Device Health” on the classic App but still no luck. Is there anything I need to do to enable that? thx!
The notification is broken for some users, including myself. I would still call the support, though.
I reported to support few days ago and sent them another email yesterday. So far, no response yet. May be I should look at Hubitat instead 
They don’t even have a broken offline notification. 