Moon Invoice allow you to check the activity log of your customers such as delivered and viewed email.

Here are the steps to go.

1. Open the Moon Invoice application on your device or tap on this link.

2. Navigate to Sales => Invoices => Click on three-dot menu => find the activity log.

3. In Activity Log, you can enable it if you want to track your sent, delivered or viewed emails.

                                                                                                                                           - Moon Invoice