SELECT
               AR_Customer_Contact.Customer_Contact_Id, AR_Customer_Contact.E_Mail, AR_Customer_1.Customer_Number,
               AR_Customer.Customer_Number AS Expr1
FROM  AR_Customer_Contact LEFT OUTER JOIN
               AR_Site_Contact INNER JOIN
               AR_Customer_Site ON AR_Site_Contact.Site_Id = AR_Customer_Site.Customer_Site_Id INNER JOIN
               AR_Customer AS AR_Customer_1 ON AR_Customer_Site.Customer_Id = AR_Customer_1.Customer_Id ON
               AR_Customer_Contact.Customer_Contact_Id = AR_Site_Contact.Site_Contact_Id LEFT OUTER JOIN
               AR_Customer_Bill INNER JOIN
               AR_Customer ON AR_Customer_Bill.Customer_Id = AR_Customer.Customer_Id INNER JOIN
               AR_Bill_Contact ON AR_Customer_Bill.Customer_Bill_Id = AR_Bill_Contact.Bill_Id ON
               AR_Customer_Contact.Customer_Contact_Id = AR_Bill_Contact.Contact_Id
WHERE (AR_Customer_Contact.E_Mail <> '') AND (AR_Customer_1.Customer_Number IS NULL)