var currUser = new List<string> { "123@qq.com" , "123@qq.com" , "123@qq.com" }；// 单个

            var title = "test";

            var content = "hello word";

            mh.SendSMTPEMail(currUser, title, content);

    public class MailHelper

    {

        private string emailAcount = ConfigurationManager.AppSettings["EmailAcount"];

        private string emailPassword = ConfigurationManager.AppSettings["EmailPassword"];

        private string emailSmart = ConfigurationManager.AppSettings["EmailSmart"];

        public void SendSMTPEMail(string strto, string strSubject, string strBody)

        {

            System.Net.Mail.SmtpClient client = new System.Net.Mail.SmtpClient(emailSmart);

            client.UseDefaultCredentials = false;

            client.EnableSsl = true;

            client.Credentials = new System.Net.NetworkCredential(emailAcount, emailPassword);

            client.DeliveryMethod = SmtpDeliveryMethod.Network;

            System.Net.Mail.MailMessage message = new System.Net.Mail.MailMessage(emailAcount, strto, strSubject, strBody);

            message.BodyEncoding = System.Text.Encoding.UTF8;

            message.IsBodyHtml = true;

            //使用文件路径发送附件

            //AlternateView item = new AlternateView(@"D:\\软件\\(软电话)eyebeam1.5.rar", "application/x-rar-compressed");

            //message.AlternateViews.Add(item);

            //message.AlternateViews.Dispose();

            //使用Stream发送附件

            //Attachment letter = new Attachment(FileUploadLetter.FileContent, FileUploadLetter.PostedFile.ContentType);

            //letter.ContentDisposition.Inline = true;

            //letter.ContentDisposition.DispositionType = DispositionTypeNames.Inline;

            ////inline.ContentId = "1";

            //letter.ContentType.MediaType = FileUploadLetter.PostedFile.ContentType;

            //letter.ContentType.Name = Path.GetFileName(FileUploadLetter.PostedFile.FileName);

            //letter.Name = Path.GetFileName(FileUploadLetter.PostedFile.FileName);

            //message.Attachments.Add(letter);

            //message.Attachments.Dispose();

            client.Send(message);

        }

        public void SendSMTPEMail(List<string> strto, string strSubject, string strBody)

        {

            System.Net.Mail.SmtpClient client = new System.Net.Mail.SmtpClient(emailSmart);

            client.UseDefaultCredentials = false;

            client.EnableSsl = true;

            client.Credentials = new System.Net.NetworkCredential(emailAcount, emailPassword);

            client.DeliveryMethod = SmtpDeliveryMethod.Network;

            foreach (var str in strto)

            {

                try

                {

                    System.Net.Mail.MailMessage message = new System.Net.Mail.MailMessage(emailAcount, str, strSubject, strBody);

                    message.BodyEncoding = System.Text.Encoding.UTF8;

                    message.IsBodyHtml = true;

                    client.Send(message);

                }

                catch

                {

                }

            }

        }

    }