C# 163邮箱发送 附件以及邮件信息

  public static bool SendEmail(EmailInfo mailInfo)
        {
            try
            {
                MailMessage mailMsg = new MailMessage();
                mailMsg.To.Add(new MailAddress(mailInfo.ToAddress));
                mailMsg.From = new MailAddress(mailInfo.FromAddress, mailInfo.DisplayName);
                mailMsg.Subject = mailInfo.Subject;
                mailMsg.AlternateViews.Add(AlternateView.CreateAlternateViewFromString(mailInfo.Body, Encoding.UTF8, MediaTypeNames.Text.Html));
                SmtpClient smtpClient = new SmtpClient(mailInfo.SmtpHost, mailInfo.SmtpPort);
                System.Net.NetworkCredential credentials = new System.Net.NetworkCredential(mailInfo.SmtpUserName, mailInfo.SmtpPassword);
                smtpClient.Credentials = credentials;
                if (!string.IsNullOrEmpty(mailInfo?.filename) && mailInfo?.stream != null)
                {
                    mailMsg.Attachments.Add(new Attachment(mailInfo.stream, mailInfo.filename));
                }
                smtpClient.Send(mailMsg);
            }
            catch (Exception ex)
            {
                return false;
            }
            return true;
        }

 public class EmailInfo
    {
        /// <summary>
        /// 收件人地址
        /// </summary>
        public string ToAddress { get; set; }
        /// <summary>
        /// 发件人地址
        /// </summary>
        public string FromAddress { get; set; }
        /// <summary>
        /// 显示名称
        /// </summary>
        public string DisplayName { get; set; }
        /// <summary>
        /// 邮件主题
        /// </summary>
        public string Subject { get; set; }
        /// <summary>
        /// SMTP服务器地址
        /// </summary>
        public string SmtpHost { get; set; }
        /// <summary>
        /// SMTP服务器端口
        /// </summary>
        public int SmtpPort { get; set; }
        /// <summary>
        /// SMTP服务器用户名
        /// </summary>
        public string SmtpUserName { get; set; }
        /// <summary>
        /// SMTP服务器密码
        /// </summary>
        public string SmtpPassword { get; set; }
        /// <summary>
        /// 邮件正文内容
        /// </summary>
        public string Body { get; set; }

        /// <summary>
        /// 附件 附件名字必填
        /// </summary>
        public Stream stream { get; set; }

        /// <summary>
        /// 附件名字：带后缀的
        /// </summary>
        public string filename { get; set; }
    }

附件依赖于 NPOI

public static MemoryStream ExportCompanyOrder()
        {
            List<car_company_orderEntity> list = new List<car_company_orderEntity>();
            for (int i = 0; i < 100; i++)
            {
                list.Add(new car_company_orderEntity() { car_company_order_id = i, company_name = "测试" + i });
            }

            //创建Excel文件的对象
            NPOI.HSSF.UserModel.HSSFWorkbook book = new NPOI.HSSF.UserModel.HSSFWorkbook();
            //添加一个sheet
            NPOI.SS.UserModel.ISheet sheet1 = book.CreateSheet("Sheet1");
            //给sheet1添加第一行的头部标题
            NPOI.SS.UserModel.IRow row1 = sheet1.CreateRow(0);
            row1.CreateCell(0).SetCellValue("ID");
            row1.CreateCell(1).SetCellValue("授权商名称");

            //将数据逐步写入sheet1各个行
            for (int i = 0; i < list.Count(); i++)
            {
                NPOI.SS.UserModel.IRow rowtemp = sheet1.CreateRow(i + 1);
                rowtemp.CreateCell(0).SetCellValue(list[i]?.car_company_order_id.ToString()); //ID
                rowtemp.CreateCell(1).SetCellValue(list[i]?.company_name); //授权商名称
            }
            // 写入到客户端
            System.IO.MemoryStream ms = new System.IO.MemoryStream();
            book.Write(ms);
            ms.Seek(0, SeekOrigin.Begin);
            return ms;
        }

  var mailInfo = new EmailInfo();
            mailInfo.SmtpHost = "smtp.163.com";
            //mailInfo.SmtpPort = 25;
            mailInfo.SmtpUserName = "[email protected]";
            mailInfo.SmtpPassword = "cheng1993";
            mailInfo.DisplayName = "智领";
            mailInfo.FromAddress = "[email protected]";
            mailInfo.ToAddress = "[email protected]";
            mailInfo.Subject = "测试";
            mailInfo.Body = "测试的啊 ";
            mailInfo.filename = "111.xls";
            mailInfo.stream = ExportCompanyOrder();
            var aa = SendEmail(mailInfo);

demo 用来测试，以及发送。 注意：163后端需要在 开启客户端授权密码

原文地址：https://www.cnblogs.com/ichengq/p/10679232.html