When you decide to take on a sweepstakes entry hobby you should consider some level of privacy for yourself. Most sites on the internet that advertise or who host sweepstakes should have a privacy policy. A Privacy policy will detail what sites will do with your personal information. Even some sweepstakes rules will indicate what they will do with your personal information.
Some sweepstakes enthusiasts would rather not enter sweepstakes when they find out that their personal information will be shared with partners. The levels of information being shared may differ from site to site. You can protect your privacy in some simple ways that will retain your sweepstakes entry. The object being protect your privacy while allowing the sweepstakes sponsor to effectively contact you if you win.
The first easy way to do this is with a separate email account that you use only for sweepstakes entry. This email account will not be used for personal or family email but sweepstakes entry forms only. If a sweepstakes form asks for your telephone number you can setup a free Google Voice account and use that new number for sweepstakes entry. You could also get a Magic Jack account and use that phone number.
Finally to protect your mailing address you could obtain a P.O. Box. If your privacy is very important a P.O. box can be setup and your local post office for a low monthly fee. The level of privacy that you require with your sweepstakes hobby will dictate how many protective measures you take. Personally I've had a good deal of privacy just by entering only name brand recognized sweepstakes and using a dedicated email account.