The checks on all the Fields and scores being given are active on three levels regarding the user the mail is sent to.
First of all the checker gets all the rules that apply to ALL users (where Account = ALL) and checks the email message for those rules. After that it gets all the rules for the group the user is a member of. If the User isn't in a group this step gets skipped. Finally all the rules for the Individual User are being applied to the email.