A new data list has been created to search by email based on the ad-hoc query 'Find records by email address query'. This ad-hoc query takes email address as an argument and returns the associated constituent and their Lookup ID. You can then save the query as a data list on the last query tab and select the email address as a search parameter.
The data list must also have the user assigned to it. A new security role 'SmartSYNC' is added just for this task. Rights were assigned to a this role 'SmartSYNC' to which the user was also added: