C # send emails requiring smtp authentication

------------------------- Call class -----------------------------------
Private void SendMaill (string username, string superpassword, string email ){
String body = "Dear User: <br> hello! <Br> & nbsp; your logon username is: "+ username +" this is your super password: "+ superpassword
+ "To ensure the security of your account, we recommend that you modify the email on the official website and delete it within 72 hours after receiving the email. "
+ "<Br>"
+ "If you have any questions, please call the customer service hotline of XXX Development Co., Ltd.: 028-xxx. We will give you a warm answer. "
+ "Thank you for your support! <Br>"
+ "& Nbsp; & nbsp; & nbsp; & nbsp; ×××××× Development Co., Ltd. <br>"
+ "& Nbsp; & nbsp; & nbsp; & nbsp; "+ System. dateTime. now. year + "Year" + System. dateTime. now. month + "Month" + System. dateTime. now. day + "Day <br>"