As I have said in the past, you are running a professional medical practice, not a friendship organization. Thus, you should not be sending out emails addressed to your patients by their first names. Be professional. It is Dr. Mr., Ms., Miss, Mrs., Professor, General, etc., etc., added to the last name. Our society is entirely too familiar and lacking in proper etiquette. Don't add to the problem. And I would appreciate receiving a proper response from whomever it is who decided to use the familiar first name form rather than the proper title and last name.