Have you received a payment notification email which states the following in the 3D Secure Validation Check section?
3D Secure Validation Check: "No Authentication Attempted - Card not enrolled"
This means the payment you have received does not have 3D-Secure fraud protection.
When you receive a payment you can only have 3D-Secure fraud protection if the cardholder/card company have the 3-DS programme enabled.
If the cardholder is not enrolled in the 3-DS programme we cannot attempt to process the transaction through the 3-DS protocol.
On this occasion the cardholder / card company were not 3-DS programme enabled.
Unfortunately, this means you are not protected against fraud.
For more information about how to spot possible fraud click here.