Don't believe that E-mail, because the American Government is still not using the E-Mails to inform winners. They got your E-mail address from a public place like forum, pen pal web sites or in some web site where you became as a member to use their facilities and the web site owner or administrators has sold your email address to these crook people. If you look good it will state you as "Dear winner" as they don't know your name. Also you will find the American Government departments and other offices in the E-mail. But the place they want you to send money is not the American Government addresses. It will be some crook persons address where they want to collect the money for their personal use. Don't answer to the E-mail or don't try to contact them at the given telephone number.
Then how will they notify me if i am a winner? If you are selected by the computer in the random draw, between May an July they will use regular mail to inform you with further instructions and the related non refundable visas fee and diversity visa processing fee.
The address you gave in the entry form will be used to send the mail. If happened to move from your original address then you must ask someone in the original address to collect any mails coming in your name in that period.