Preferred email is a secondary email field that is available to users who authenticate to a digital workplace using SSO. This Preferred Email address is where all workplace notifications get sent. Unless changed, a user's Preferred Email will be the same as their account email. Users can change their preferred from the Email Settings page of their Personal Profile.
Administrators can view the Preferred Emails of users by exporting the workplace's member list. The resulting CSV file contains a column for Preferred Email.