When setting up your NPS campaign, you will have the option to select who the NPS survey is sent from and that field is called "Send Message From". If you select "Account Owner", and the "Account Owner" doesn't have their emails synced, then the email will not be sent. The email will be stored in the "Outgoing - need action" folder of the Email Manager.
You will see the following error message: "Send error: Access to Gmail account not enabled yet for the sender!".
✔️Solution
The "Account Owner" needs to sync their emails, following these instructions.
As soon as you have synced your emails, you just need to locate the email in the "Outgoing - need action" folder and click on the tick mark icon to approve the email. That's it, your NPS survey should send within the next 10 minutes.👍