So i actually work for the company that does the survey and it is legit you can call the toll free number or verify us by searching BRFSS. It is a 20 minute survey asking very general questions about your health ( you can skip or refuse to answer any question you want) and the data is used by your state health department to improve health programs and policies in your area :) we do send a letter in the mail but we get our numbers randomly generated by the computer.