Hubitat Elevation includes a built-in email notification driver, which allows the hub to send email via many popular email providers or any SMTP server. Such devices are usable in automation and other apps in the same way as a notification device, which allows flexible usage from apps such as Notifications, Rule Machine, and many others.
For setup instructions and discussion, see:
https://community.hubitat.com/t/new-email-notification-driver-for-sending-email-alerts/164415