Getting users to sign up.
D001292:Attitude to Computers; D004059:Diffusion of Innovation; D034742:Electronic Mail; D006801:Humans; D020407:Internet / Q000706:statistics & numerical data*; D016347:Medical Records Systems, Computerized; D011216:Practice Management, Medical / Q000458:organization & administration; D011320:Primary Health Care / Q000458:organization & administration*; D014481:United States