There could be several reasons why your customers are not receiving email notifications from Receptive.
The first thing you should check is that you haven't disabled them. Head to Settings > Email and Whitelabel and make sure the first checkbox is unticked.
If that box is unchecked and your customers still aren't receiving email notifications, then it might be because they haven't authorized emails from Receptive.
NOTE: Customers added through the integration don't need to authorize emails, so if you've integrated this next step won't apply.
You can re-send the invite to a customer who isn't receiving emails by heading to Customers and clicking on "New customer / prospect".
Enter their details and you should see the following notice:
Your customer will need to authorize emails from Receptive by clicking the link in the email.
If you've worked through the steps above and your customers still aren't receiving email notifications, then get in touch and we'll get to the bottom of it.