C#发送正文带图片带附件的邮件

1，开启服务，获取授权码。以QQ邮箱为例：

点击管理服务，进入账号与安全页面

 2，相关设置参数，以QQ邮箱为例：

登录时，请在第三方客户端的密码输入框里面填入授权码进行验证。（不是填入QQ的密码）
IMAP/SMTP 设置方法用户名/帐户： 你的QQ邮箱完整的地址密码： 生成的授权码电子邮件地址： 你的QQ邮箱的完整邮件地址接收邮件服务器： imap.qq.com，使用SSL，端口号993发送邮件服务器： smtp.qq.com，使用SSL，端口号587POP3/SMTP 设置方法用户名/帐户： 你的QQ邮箱完整的地址密码： 生成的授权码电子邮件地址： 你的QQ邮箱的完整邮件地址接收邮件服务器： pop.qq.com，使用SSL，端口号995发送邮件服务器： smtp.qq.com，使用SSL，端口号587

3，2次包装代码：

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Net.Mail;
using System.Net.Mime;
using System.Text;
using System.Text.RegularExpressions;
using System.Threading.Tasks;
namespace Common
{/// <summary>/// 软件的邮箱类，用于发送邮箱数据/// </summary>public class Emailhelp{public static Emailhelp MailSystem163 = new Emailhelp(mail =>{mail.Host = "smtp.163.com";//使用163的SMTP服务器发送邮件//mail.UseDefaultCredentials = true;//在winform平台使用默认值mail.EnableSsl = true;mail.UseDefaultCredentials = false;//在.framework或mvc下使用这个mail.Port = 25;//端口号mail.DeliveryMethod = SmtpDeliveryMethod.Network;mail.Credentials = new System.Net.NetworkCredential("邮件发送地址（自己的邮件号）如[e-mail]", "刚才获取的授权码");},"邮件发送地址（自己的邮件号）如[e-mail]","邮件发送地址（自己的邮件号）如[e-mail]");/// <summary>/// 系统连续发送失败的次数，为了不影响系统，连续三次失败就禁止发送/// </summary>private static long SoftMailSendFailedCount { get; set; } = 0L;/// <summary>/// 系统的邮件发送客户端/// </summary>private SmtpClient smtpClient { get; set; }/// <summary>/// 发送邮件的地址/// </summary>private string MailFromAddress { get; set; } = "";/// <summary>/// 邮件发送的地址/// </summary>public string MailSendAddress { get; set; } = "";/// <summary>/// 实例化一个邮箱发送类，需要指定初始化信息/// </summary>/// <param name="mailIni">初始化的方法</param>/// <param name="addr_From">发送地址，应该和账户匹配</param>/// <param name="addr_to">邮件接收地址</param>/// <remarks>/// </remarks>public Emailhelp(Action<SmtpClient> mailIni, string addr_From = "", string addr_to = ""){smtpClient = new SmtpClient();mailIni(smtpClient);MailFromAddress = addr_From;MailSendAddress = addr_to;}private string GetExceptionMail(Exception ex){return ex.Message;}/// <summary>/// 发送邮件/// </summary>/// <param name="addr_from">发送地址</param>/// <param name="name">发送别名</param>/// <param name="addr_to">接收地址</param>/// <param name="subject">邮件主题</param>/// <param name="body">邮件内容</param>/// <param name="attachment">附件地址</param>/// <param name="isHtml">邮件内容是否是HTML语言</param>/// <param name="priority">优先级</param>/// <returns>发生是否成功，内容不正确会被视为垃圾邮件</returns>public bool SendMail(string addr_from, string name, string[] addr_to, string subject, string body, string[] attachment, bool isHtml = false, MailPriority priority = MailPriority.Normal){if (SoftMailSendFailedCount > 10){SoftMailSendFailedCount++;return true;}MailMessage mailMessage = new MailMessage();try{mailMessage.From = new MailAddress(addr_from, name, Encoding.UTF8);foreach (string addresses in addr_to){mailMessage.To.Add(addresses);}mailMessage.Subject = subject;mailMessage.Body = body;MailMessage mailMessage2 = mailMessage;mailMessage2.Body = mailMessage2.Body + Environment.NewLine + Environment.NewLine + Environment.NewLine;mailMessage.SubjectEncoding = Encoding.UTF8;mailMessage.BodyEncoding = Encoding.UTF8;mailMessage.Priority = priority;mailMessage.IsBodyHtml = isHtml;for (int i = 0; i < attachment.Length; i++){Attachment address = new Attachment(attachment[i]);mailMessage.Attachments.Add(address);}smtpClient.Send(mailMessage);SoftMailSendFailedCount = 0L;return true;}catch (Exception ex){SoftMailSendFailedCount++;return false;}}/// <summary>/// 发送内容带有图片的邮件/// </summary>/// <param name="sfrom">发件人邮箱地址</param>/// <param name="displayName">显示名</param>/// <param name="addr_to">收件人地址</param>/// <param name="sSubject">标题</param>/// <param name="sBody">邮件内容</param>/// <param name="attachment">邮件附件</param>/// <returns></returns>public bool Send(string sfrom, string displayName, string[] addr_to, string sSubject, string sBody, string[] attachment){MailMessage oMail = new MailMessage();oMail.From = new MailAddress(sfrom, displayName, Encoding.UTF8);foreach (var item in addr_to){oMail.To.Add(item);}//  添加附件if (attachment != null){foreach (var item in attachment){oMail.Attachments.Add(new Attachment(item));}}sBody = ReplaceImg(sBody, oMail);  // 处理图片oMail.Subject = sSubject;  //邮件标题oMail.Body = sBody;   //邮件内容oMail.IsBodyHtml = true;  //邮件格式oMail.BodyEncoding = Encoding.GetEncoding("GB2312");  //邮件采用的编码oMail.Priority = MailPriority.High;  //设置邮件的优先级为高try{smtpClient.Send(oMail);return true;}catch (Exception e){SoftMailSendFailedCount++;return false;}finally{oMail.Dispose();  //释放资源}}/// <summary>/// 处理邮件内容中的图片/// 将图片改为附件形式在body中显示/// </summary>/// <param name="body"></param>/// <returns></returns>private string ReplaceImg(string body, MailMessage m){try{Dictionary<string, Stream> imgDic = new Dictionary<string, Stream>();body = GetImgStream(body, imgDic);AlternateView avHtml = AlternateView.CreateAlternateViewFromString(body, null, MediaTypeNames.Text.Html);if (imgDic.Count != 0) // 内容添加图片{foreach (var dic in imgDic){LinkedResource lrImage = new LinkedResource(dic.Value, "image/gif");lrImage.ContentId = dic.Key;avHtml.LinkedResources.Add(lrImage);}}m.AlternateViews.Add(avHtml);return body;}catch (Exception){return body;}}private string GetImgStream(string body, Dictionary<string, Stream> imgDic){string mactch;Regex reg = new Regex(@"(?i)<img[^>]*?\ssrc\s*=\s*(['""]?)(?<src>[^'""\s>]+)\1[^>]*>");MatchCollection mc = reg.Matches(body);for (int i = 0; i < mc.Count; i++){string key = "pic" + i;mactch = mc[i].Groups["src"].Value;body = body.Replace(mactch, "cid:" + key);FileStream fs = new FileStream(mactch, FileMode.Open);imgDic.Add(key, fs);}return body;}}
}

4，邮件效果：

特别说明：若要实现：

第1，正文带有背景图片。
第2，正文为自定义编辑风格（带有边框，不同颜色的字体）。
正文需要为html格式，普通文本格式无法实现。