A simple SOQL on NetworkMember object can be used to find Email Preferences of the Salesforce Experience Cloud Site Users
Sample SOQL:
SELECT Id, Network.Name, Member.Name, DigestFrequency, PreferencesDisableAllFeedsEmail, PreferencesDisableBestAnswerEmail, PreferencesDisableBookmarkEmail, PreferencesDisableChangeCommentEmail, PreferencesDisableDirectMessageEmail, PreferencesDisableEndorsementEmail, PreferencesDisableFollowersEmail, PreferencesDisableItemFlaggedEmail, PreferencesDisableLaterCommentEmail, PreferencesDisableLikeEmail, PreferencesDisableMentionsPostEmail, PreferencesDisableMessageEmail, PreferencesDisableProfilePostEmail, PreferencesDisableSharePostEmail, PreferencesDisCommentAfterLikeEmail, PreferencesDisMentionsCommentEmail, PreferencesDisProfPostCommentEmail
FROM NetworkMemberOutput:
