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 by typing ‘Customer ID’ into the search bar of the Modules 
menu.
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.