C# 邮件发送

SMTP(Simple Mail Transport Protocol)简单邮件传输协议。在.NET Frameword类库中提供SmtpClient类(System.NET.Mail)，提供了一个轻型方法来发送SMTP电子邮件信息。

1.首先引入命名空间using System.Net.Mail;

2.将发送的邮件的功能封装成一个类，该类中包含了发送邮件的基本功能：收件人(多人)，抄送(多人)，发送人，主题，邮件正文，附件等，封装的Email类如下：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net.Mail;
using System.Text;
using System.Threading.Tasks;

namespace Helper
{
    /// <summary>
    /// 发送邮件辅助类
    /// </summary>
    public class EmailHelper
    {
        /// <summary>
        /// 发送者
        /// </summary>
        public string MailFrom { get; set; }

        /// <summary>
        /// 收件人
        /// </summary>
        public string[] MailToArray { get; set; }

        /// <summary>
        /// 抄送
        /// </summary>
        public string[] MailCcArray { get; set; }

        /// <summary>
        /// 标题
        /// </summary>
        public string MailSubject { get; set; }

        /// <summary>
        /// 正文
        /// </summary>
        public string MailBody { get; set; }

        /// <summary>
        /// 发件人密码
        /// </summary>
        public string MailPwd { get; set; }

        /// <summary>
        /// SMTP邮件服务器
        /// </summary>
        public string Host { get; set; }

        /// <summary>
        /// 正文是否是html格式
        /// </summary>
        public bool IsbodyHtml { get; set; }

        /// <summary>
        /// 附件,附件的文件路径
        /// </summary>
        public string[] AttachmentsPath { get; set; }

        public bool Send()
        {
            //使用指定的邮件地址初始化MailAddress实例
            MailAddress maddr = new MailAddress(MailFrom);
            //初始化MailMessage实例
            MailMessage myMail = new MailMessage();

            //向收件人地址集合添加邮件地址
            if (MailToArray != null)
            {
                for (int i = 0; i < MailToArray.Length; i++)
                {
                    myMail.To.Add(MailToArray[i].ToString());
                }
            }
            //向抄送收件人地址集合添加邮件地址
            if (MailCcArray != null)
            {
                for (int i = 0; i < MailCcArray.Length; i++)
                {
                    myMail.CC.Add(MailCcArray[i].ToString());
                }
            }
            //发件人地址
            myMail.From = maddr;
            //电子邮件的标题
            myMail.Subject = MailSubject;
            //电子邮件的主题内容使用的编码
            myMail.SubjectEncoding = Encoding.UTF8;

            //电子邮件正文
            myMail.Body = MailBody;
            //电子邮件正文的编码
            myMail.BodyEncoding = Encoding.Default;

            myMail.Priority = MailPriority.High;
            myMail.IsBodyHtml = IsbodyHtml;

            //在有附件的情况下添加附件
            try
            {
                if (AttachmentsPath != null && AttachmentsPath.Length > 0)
                {
                    Attachment attachFile = null;
                    foreach (string path in AttachmentsPath)
                    {
                        attachFile = new Attachment(path);
                        myMail.Attachments.Add(attachFile);
                    }
                }
            }
            catch (Exception err)
            {
                throw new Exception("在添加附件时有错误:" + err);
            }

            SmtpClient smtp = new SmtpClient
            {
                EnableSsl = true,
                UseDefaultCredentials = false,
                DeliveryMethod = SmtpDeliveryMethod.Network,

                //设置SMTP邮件服务器
                Host = Host,
                //指定发件人的邮件地址和密码以验证发件人身份
                Credentials = new System.Net.NetworkCredential(MailFrom, MailPwd),

            };

            try
            {
                //将邮件发送到SMTP邮件服务器
                smtp.Send(myMail);
                return true;
            }
            catch (SmtpException ex)
            {
                throw ex;
            }
        }
    }
}

 注意：一定要先设置 EnableSsl和UseDefaultCredentials，再实例化Credentials 

3、调用发送邮件的类

 [TestMethod]
        public void TestEmail()
        {
            LogModel log = new LogModel()
            {
                ProjectName = ProjectName.Helper,
                MethodName = "TestEmail",
                Meassage = ""
            };
            bool result = false;
            try
            {
                string info = "摄像头005异常。上次状态正常时间是：" + DateTime.Now.AddDays(-1).ToString();
                //发邮件
                EmailHelper email = new EmailHelper
                {
                    MailFrom = "xxxxx@qq.com",
                    MailPwd = "matxacxgfghnbhhf", //我的qq邮箱授权码
                    MailSubject = "设备异常",
                    MailBody = info,
                    //email.isbodyHtml = true;    //是否是HTML
                    Host = "smtp.qq.com",    //如果是QQ邮箱则：smtp:qq.com,依次类推  genvict不行
                    MailToArray = new string[] { "Ziyouxxx@163.com" },//接收者邮件集合
                    MailCcArray = new string[] { "huxxxxx@163.com" }, //抄送者邮件集合
                    AttachmentsPath=new string[] { @"F:MyZoneWeWeixin.jpg", @"F:learn_newElasticSearch高吞吐ELK实践_携程旅行_吴晓刚_[Remark].pdf" },
                };
                result = email.Send();

                //逻辑代码...
                string isExistStr = result == true ? "成功" : "失败";
                log.Meassage = $"邮件发送{isExistStr}";
                FileToELK.WriteLogToELK(log);
            }
            catch (Exception ex)
            {
                log.logType = LogType.Error;
                log.Meassage = ex.ToString();
                FileToELK.WriteLogToELK(log);
                result = false;
            }
            Assert.IsTrue(result);
        }

问题1：Smpt命令顺序不正确。 服务器响应为: Error: need EHLO and AUTH first !

原因：未加（ EnableSsl  SSL加密连接 ）导致的

问题2：服务器响应为: mail from address must be same as authorization user

原因：授权码不对。

QQ邮箱中设置授权码，（其他的邮箱相应设置）

1、首先在QQ邮箱当中开启“POP3/SMTP服务”

2、获取“授权码”

　　在上一步刚开通后也会提示出“授权码”，单击生成授权码。