For Site Users to receive email notifications when their accounts are added to a site, must have the following columns in the import spreadsheet set to "TRUE" (without quotes):
- Receive Notifications
However, if you're updating existing Site Users, no email notifications will be sent out because their accounts have been "Approved" prior to importing. In order to trigger a new email notification to be sent out, you would need to first import the spreadsheet with the column "Approved" set to "FALSE" (no quotes), then re-import a 2nd time with the column "Approved" set to "TRUE" (no quotes).
By doing this, you are recreating the scenario of a new account being created, and approved, which then triggers the Email Notification to be sent out.