This plugin creates extends WooCommerce by letting the guest user confirm thier email and combine orders when guest users use the same email.
An extra email field is created for guest users in the checkout screen. During the checkout the provided emails are checked if they are corresponding.
This check is done in the front-end by Javascript and in the AJAX call with php.
During the checkout as a guest the guest account is saved so when this customer will create a account later all the old orders are linked to this customer.
In the admin there is a ‘created_by_webshop’ column that will display yes when the user was a guest and it’s created by the system.