Theoretically you should receive both approval/denial by mail and e-mail notification. My I-140 petition was approved on May 31, 2005 (see my signature below). I have received I-140 approval, Form I-797, by mail (through my employer). My I-140 LUD (Last Updated Date) was changed on June 1, 2005, but no change in the message. USCIS online status still shows pending: “Your I140 IMMIGRANT PETITION FOR ALIEN WORKER was received on March 3, 2005 ...” (I had no RFE). I also didn't receive an email from USCIS. Apparently online case status information is not working properly. I talked to customer service at USCIS and they explained that USCIS has some issue with updating the database.