Registering with survey companies generates a lot of email. Consistently using only the email address you have dedicated to surveys will help you keep organized. You may have to sift through some unwanted offers before locating survey opportunities to which you wish to respond.
Some survey sites may have checkboxes on the registration page which are checked by default, indicating that you agree to receive additional information about other offers, or that you agree to share your profile information with other sites. If you are not interested in these offers, unchecking the boxes can reduce the amount of non-survey email you receive.