Antavo’s Customer ID validation mechanism allows the creation of anonymous events, which means that an event can be registered without a customer ID value in the customer attribute of the event.
Find the configuration page of the Customer ID validation module under the Modules 
menu.
Guest events
The interface has only one configuration option.
If the ‘Guest events’ checkbox is enabled and an incoming event has the {{guest: true}} flag, the following options can happen:
the customer is not included in the event request: Antavo considers it as an anonymous event, no customer will be created or updated, and the event will not contain a
customerpropertythe customer is included in the event request: the error
BadRequestExceptionis returned, as it is not possible to send a guest event with a customer
If the ‘Guest events’ checkbox is not marked or no {{guest: true}} flag is present, the default mechanism will apply meaning that all requests without customer property will fail.
Read more about guest transactions in our API docs here.
Automatic customer ID generation
If the Customer ID validation is turned on, the customer ID is automatically generated when you add a new customer manually under the Customer insights menu.
The generated ID cannot be modified with manual registration, however you’ll still be able to register customers with any customer ID via opt_in events, through the Events API.