Interesting. This looks like a recent change. Apparently I can no longer use workflow to send emails to people who never logged into, nor, used Smartsheet, ever. Has anyone found a way to let emails be used in workflows such as alerts, update requests, etc? Every single one is now generating errors for the users who don't have SS accounts despite being unrestricted.
Here's my unrestricted settings:
Here's the alert from Smartsheet: