There isn't a built-in mail server on our hubs. As noted, there are community solutions along with built-in ones that might meet your needs. I have added links to a couple of them below, but I haven't used any of these so I don't know how they will work for your requirements.
Pushover is a third-party cloud-based service that can provide real-time notifications on your Android or iOS mobile device or computer. It can be used as a notification device on Hubitat as an alternative (or supplement) to the Hubitat mobile app or other methods of receiving notifications .Pushover | Hubitat Documentation)
