Custom fields in your Constant Contact account are how DataValidation stores Email Assurance Grades for your contacts. Custom fields can be edited when a list (or contact) is first upload to your Constant Contact account, within an individual contact's information, or through 'My Settings' on your dashboard.
You can see which custom field is being used by DataValidation by looking at an individual contact's information.
The Email Assurance Grade will be listed as a custom field in the following format: "custom_field_1: +dv_grade_A+ "
To view or edit custom fields for existing contacts, you'll want to do this through 'My Settings'. Once you access settings, click on 'Manage my custom settings', under 'Contact Settings.'
Be sure to leave the field used by DataValidation available, so that Email Assurance grades can populate and update within your Constant Contact account. (ie. If custom_field_1 is already taken up for extra contact data such as gender, or address, DataValidation will use the next custom field available. Be sure to leave this field available when adding new contacts.)