If you are using SQL Server 2005 or above use this:
SELECT *
FROM (
SELECT ID,
Email,
ProductName,
ProductModel,
ROW_NUMBER() OVER(PARTITION BY Email ORDER BY ID DESC) rn
FROM Products
) a
WHERE rn = 1
EDIT:
Example using a where clause:
SELECT *
FROM (
SELECT ID,
Email,
ProductName,
ProductModel,
ROW_NUMBER() OVER(PARTITION BY Email ORDER BY ID DESC) rn
FROM Products
WHERE ProductModel = 2
AND ProductName LIKE 'CYBER%'
) a
WHERE rn = 1