C#通过拼接协议的方式来发送邮件类库

 using System;
 using System.Collections.Generic;
 using System.Net;
 using System.Net.Mail;
 using System.Net.Sockets;
 using System.Text;

 namespace HR.Common
 {
     #region SMTP　Client
     public class SMTPClient : TcpClient
     {
         /// <summary>
         /// 是否链接
         /// </summary>
         /// <returns></returns>
         public bool isConnected()
         {
             return Active;
         }

         /// <summary>
         /// 向服务器发送指令
         /// </summary>
         /// <param name="Command">指令内容</param>
         public void SendCommandToServer(string Command)
         {
             NetworkStream ns = this.GetStream();
             byte[] WriteBuffer = null;
             WriteBuffer = new byte[Command.Length];
             WriteBuffer = Encoding.Default.GetBytes(Command);
             ns.Write(WriteBuffer, , WriteBuffer.Length);
             return;
         }

         /// <summary>
         /// 返回服务器处理结果
         /// </summary>
         /// <returns></returns>
         public string GetServerResponse()
         {
             int StreamSize;
             string ReturnValue = "";
             byte[] ReadBuffer;
             NetworkStream ns = this.GetStream();

             ReadBuffer = new byte[];
             StreamSize = ns.Read(ReadBuffer, , ReadBuffer.Length);
             if (StreamSize == )
             {
                 return ReturnValue;
             }
             else
             {
                 ReturnValue = Encoding.Default.GetString(ReadBuffer);
                 return ReturnValue;
             }
         }

         /// <summary>
         /// 生成SMTPCode
         /// </summary>
         /// <param name="s">信息内容</param>
         /// <param name="SMTPCode">SMTPCode</param>
         /// <returns></returns>
         public bool DoesStringContainSMTPCode(string s, string SMTPCode)
         {
             return (s.IndexOf(SMTPCode, , ) == -) ? false : true;
         }

     }
     #endregion

     #region SckMail
     public class SckMail
     {
         /// <summary>
         /// 邮件发送优先级权举表
         /// </summary>
         public enum Prioritys
         {
             /// <summary>
             /// 最高级别
             /// </summary>
             HIGH = ,
             /// <summary>
             /// 默认级别
             /// </summary>
             NORMAL = ,
             /// <summary>
             /// 最低级别
             /// </summary>
             LOW =
         }

         /// <summary>
         /// 构造函数
         /// </summary>
         public SckMail()
         {
             strErrMessage = "";
             strResponse = "";
         }

         #region "返回信息"

         /// <summary>
         /// SMTP服务器反馈的信息
         /// </summary>
         private string strResponse = "";

         /// <summary>
         /// 取得SMTP服务器反馈的信息
         /// </summary>
         public string ServerResponse
         {
             get
             {
                 return strResponse;
             }
         }

         /// <summary>
         /// 错误反馈信息
         /// </summary>
         private string strErrMessage = "";

         /// <summary>
         /// 取得错误反馈信息
         /// </summary>
         public string ErrorMessage
         {
             get
             {
                 return strErrMessage;
             }
         }

         /// <summary>
         /// 认证用户名
         /// </summary>
         private string strUsername = "";

         /// <summary>
         /// 认证用户名
         /// </summary>
         public string Username
         {
             get { return strUsername; }
             set { strUsername = value; }
         }

         /// <summary>
         /// 认证密码
         /// </summary>
         private string strPassword = "";

         /// <summary>
         /// 认证密码
         /// </summary>
         public string Password
         {
             get { return strPassword; }
             set { strPassword = value; }
         }

         #endregion

         #region "邮件属性"

         /// <summary>
         /// SMTP 邮件服务器
         /// </summary>
         private string _SmtpHost = "";

         /// <summary>
         /// SMTP 邮件服务器
         /// </summary>
         public string SmtpHost
         {
             get
             {
                 return _SmtpHost;
             }
             set
             {
                 _SmtpHost = value;
             }
         }

         /// <summary>
         /// SMTP邮件服务器端口
         /// </summary>
         private int _Port = ;

         /// <summary>
         /// SMTP邮件服务器端口
         /// </summary>
         public int Port
         {
             get
             {
                 return _Port;
             }
             set
             {
                 _Port = value;
             }
         }

         #endregion

         /// <summary>
         /// Base64加密
         /// </summary>
         /// <param name="code">明文</param>
         /// <returns>密文</returns>
         public string MailBase64(string code)
         {
             string encode = "";
             try
             {
                 byte[] bytes = Encoding.GetEncoding(Encoding.Default.CodePage).GetBytes(code);
                 encode = Convert.ToBase64String(bytes);
             }
             catch (Exception ex)
             {
                 //utils.LastError = ex;
                 encode = code;
             }
             return encode;
         }

         /// <summary>
         /// Socket发送邮件
         /// </summary>
         /// <param name="strFrom">发送人 邮件地址</param>
         /// <param name="strDisplayFromName">发送人显示名</param>
         /// <param name="strTo">收件人 邮件地址</param>
         /// <param name="strDisplayToName">收件人显示名</param>
         /// <param name="clsPriority">邮件优先级</param>
         /// <param name="blnHtml">是否发送HTML邮件</param>
         /// <param name="strBase">发送来源(可以为空)</param>
         /// <param name="strMessage">发送内容</param>
         /// <param name="strSubject">邮件主题</param>
         public void SendMail(string strFrom, string strDisplayFromName, string strTo, string strDisplayToName,
             Prioritys clsPriority, bool blnHtml, string strBase, string strSubject, string strMessage)
         {
             string strResponseNumber = "";
             bool bolConnect = false;
             List<string> strSendBuffer = null;
             string[] strResponseCode = { "", "", "", "", "", "", "" };   // success codes from SMTP server

             try
             {
                 strSendBuffer = new List<string>();

                 SMTPClient smtpcMail = new SMTPClient();

                 smtpcMail.Connect(_SmtpHost, _Port);
                 bolConnect = smtpcMail.isConnected();

                 //判断是否进行了连接
                 if (!bolConnect)
                 {
                     strErrMessage = "Smtp服务器连接失败...";
                     return;
                 }

                 //读取反馈信息
                 strResponseNumber = smtpcMail.GetServerResponse();
                 if (smtpcMail.DoesStringContainSMTPCode(strResponseNumber, ""))
                 {
                     this.strResponse += strResponseNumber;
                 }
                 else
                 {
                     this.strErrMessage = "连接失败:" + strResponseNumber;
                     return;
                 }

                 string strData = "";
                 strData = string.Concat("HELO ", _SmtpHost);
                 strData = string.Concat(strData, "\r\n");
                 strSendBuffer.Add(strData);

                 strData = "";
                 strData = string.Concat(strData, "AUTH LOGIN");
                 strData = string.Concat(strData, "\r\n");
                 strSendBuffer.Add(strData);

                 strData = "";
                 strData = string.Concat(strData, MailBase64(this.strUsername));
                 strData = string.Concat(strData, "\r\n");
                 strSendBuffer.Add(strData);

                 strData = "";
                 strData = string.Concat(strData, MailBase64(this.strPassword));
                 strData = string.Concat(strData, "\r\n");
                 strSendBuffer.Add(strData);

                 strData = "";
                 strData = string.Concat("MAIL FROM: ", "<" + strFrom + ">");
                 strData = string.Concat(strData, "\r\n");
                 strSendBuffer.Add(strData);

                 strData = "";
                 strData = string.Concat("RCPT TO: ", "<" + strTo + ">");
                 strData = string.Concat(strData, "\r\n");
                 strSendBuffer.Add(strData);

                 strData = "";
                 strData = string.Concat("DATA", "\r\n");
                 strSendBuffer.Add(strData);

                 strData = "";
                 strData = string.Concat("From: ", strDisplayFromName + "<" + strFrom + ">");
                 strData = string.Concat(strData, "\r\n");
                 strData = string.Concat(strData, "To: ");
                 strData = string.Concat(strData, strDisplayToName + "<" + strTo + ">");
                 strData = string.Concat(strData, "\r\n");
                 strData = string.Concat(strData, "Subject: ");
                 strData = string.Concat(strData, strSubject);
                 strData = string.Concat(strData, "\r\n");
                 strData = string.Concat(strData, "MIME-Version: 1.0");
                 strData = string.Concat(strData, "\r\n");
                 strData = string.Concat(strData, "X-Priority: " + clsPriority);
                 strData = string.Concat(strData, "\r\n");
                 strData = string.Concat(strData, "X-MSMail-Priority: " + clsPriority);
                 strData = string.Concat(strData, "\r\n");
                 if (blnHtml == true)
                 {
                     strData = string.Concat(strData, "Content-Type: text/html;");
                 }
                 else
                 {
                     strData = string.Concat(strData, "Content-Type: text/plain;");
                 }
                 strData = string.Concat(strData, "\r\n");
                 strData = string.Concat(strData, "charset=\"iso-8859-1\"");
                 strData = string.Concat(strData, "\r\n");
                 strData = string.Concat(strData, "Content-Transfer-Encoding: base64");
                 strData = string.Concat(strData, "\r\n");
                 strData = string.Concat(strData, "Content-Base: \"" + strBase + "\"");
                 strData = string.Concat(strData, "\r\n" + "\r\n");

                 strData = string.Concat(strData, MailBase64(strMessage));
                 strData = string.Concat(strData, "\r\n.\r\n");
                 strSendBuffer.Add(strData);

                 strData = "";
                 strData = string.Concat(strData, "QUIT\r\n");
                 strSendBuffer.Add(strData);
                 int i = ;

                 while (i < strSendBuffer.Count)
                 {
                     smtpcMail.SendCommandToServer(strSendBuffer[i]);
                     strResponseNumber = smtpcMail.GetServerResponse();

                     for (int j = ; j < strResponseCode.Length; j++)
                     {
                         if (smtpcMail.DoesStringContainSMTPCode(strResponseNumber, strResponseCode[j]))
                         {
                             this.strResponse += strResponseNumber;
                             this.strResponse += "<br>";
                             break;
                         }
                         else
                         {
                             if (j == strResponseCode.Length - )
                             {
                                 this.strErrMessage += strResponseNumber;
                                 this.strErrMessage += strSendBuffer[i];
                                 return;
                             }
                         }
                     }

                     i++;
                 } // 结束循环
             }
             catch (SocketException err)
             {
                 this.strErrMessage += err.Message + " " + err.StackTrace;
                 throw (err);
             }
             catch (Exception e)
             {
                 this.strErrMessage += e.Message + " " + e.StackTrace;
                 throw (e);
             }
         }

     }
     #endregion

     #region SMTPMail
     public class SMTPMail
     {
         private string smtpServer;
         private string smtpUser;
         private string smtpPwd;
         private string userEmail;
         private string subject;
         private string body;

         private int serverPort = ;    //默认为25
         private bool isHtml = false;         // 是否Html邮件

         //private string charset = "GB2312";  //设定语言代码,默认设定为GB2312,如不需要可设置为""
         //private string priority = "Normal";  //邮件发送优先级,可设置为"High","Normal","Low"

         /// <summary>
         /// 邮件服务器地址
         /// </summary>
         public string SmtpServer
         {
             get { return smtpServer; }
             set { smtpServer = value; }
         }

         /// <summary>
         /// 邮件服务器端口号
         /// </summary>
         public int ServerPort
         {
             get { return serverPort; }
             set { serverPort = value; }
         }

         /// <summary>
         /// 是否Html邮件
         /// </summary>
         public bool IsHtml
         {
             get { return isHtml; }
             set { isHtml = value; }
         }

         ///// <summary>
         ///// 代码
         ///// </summary>
         //public string Charset
         //{
         //    get { return charset; }
         //    set { charset = value; }
         //}
         ///// <summary>
         ///// 邮件发送优先级,可设置为"High","Normal","Low"或"1","3","5"
         ///// </summary>
         //public string Priority
         //{
         //    set
         //    {
         //        switch (value.ToLower())
         //        {
         //            case "high":
         //                priority = "High";
         //                break;

         //            case "1":
         //                priority = "High";
         //                break;

         //            case "normal":
         //                priority = "Normal";
         //                break;

         //            case "3":
         //                priority = "Normal";
         //                break;

         //            case "low":
         //                priority = "Low";
         //                break;

         //            case "5":
         //                priority = "Low";
         //                break;

         //            default:
         //                priority = "High";
         //                break;
         //        }
         //    }
         //}

         /// <summary>
         /// 邮件发送帐号
         /// </summary>

         public string SmtpUser
         {
             get { return smtpUser; }
             set { smtpUser = value; }
         }

         /// <summary>
         /// 邮件发送帐号密码
         /// </summary>
         public string SmtpPwd
         {
             get { return smtpPwd; }
             set { smtpPwd = value; }
         }

         /// <summary>
         /// 用户邮件地址，即是被发送人的邮件地址
         /// </summary>
         public string UserEmail
         {
             get { return userEmail; }
             set { userEmail = value; }
         }

         /// <summary>
         /// 邮件标题
         /// </summary>
         public string Subject
         {
             get { return subject; }
             set { subject = value; }
         }

         /// <summary>
         /// 邮件主体
         /// </summary>
         public string Body
         {
             get { return body; }
             set { body = value; }
         }

         /// <summary>
         /// 发送邮件
         /// </summary>
         /// <returns>bool</returns>
         public bool SendEmail()
         {
             try
             {
                 using (MailMessage mailMsg = new MailMessage(this.smtpUser, this.userEmail))
                 {
                     mailMsg.Subject = this.subject;
                     mailMsg.Body = this.body;
                     mailMsg.SubjectEncoding = Encoding.UTF8;

                     mailMsg.BodyEncoding = Encoding.UTF8;
                     mailMsg.IsBodyHtml = this.isHtml;
                     mailMsg.Priority = MailPriority.Normal;

                     SmtpClient smtpClient = new SmtpClient(this.smtpServer);
                     smtpClient.Port = this.serverPort;
                     smtpClient.UseDefaultCredentials = false;
                     smtpClient.DeliveryMethod = SmtpDeliveryMethod.Network;
                     smtpClient.Credentials = new NetworkCredential(this.smtpUser, this.smtpPwd);
                     smtpClient.Send(mailMsg);

                     return true;
                 }

             }
             catch (Exception ex)
             {

                 throw ex;
             }
         }
     }
     #endregion

     #region MailInfo
     public class MailInfo
     {
         /// <summary>
         /// 邮件服务器地址
         /// </summary>
         public string SmtpHost = string.Empty;

         /// <summary>
         /// 端口号
         /// </summary>
         public int Port = ;

         /// <summary>
         /// 邮箱登录名
         /// </summary>
         public string UserName = string.Empty;

         /// <summary>
         /// 邮箱登录密码
         /// </summary>
         public string Password = string.Empty;

         /// <summary>
         /// 发送人邮件
         /// </summary>
         public string From = string.Empty;

         /// <summary>
         /// 发送人姓名
         /// </summary>
         public string FromName = string.Empty;
         /// <summary>
         /// 获取邮件配置信息
         /// </summary>
         /// <returns></returns>
         public MailInfo GetMailInfo()
         {
             var config = System.Web.Configuration.WebConfigurationManager.AppSettings;
             MailInfo model = new MailInfo();
             model.SmtpHost = config["SmtpHost"].Trim();
             try
             {
                 if (!int.TryParse(config["SmtpPort"], out model.Port))
                 {
                     model.Port = ;
                 }
             }
             catch
             {
                 model.Port = ;
             }
             model.UserName = config["EmailUserName"];
             model.Password = config["EmailPassword"];
             model.From = config["EmailFrom"];
             model.FromName = config["EmailFromName"];
             return model;
         }
         public static string SendMail(string email, string title, string content)
         {
            // bool IsSuccess = true;
             string mailContent = string.Empty;
             string mailinfo = string.Empty;
             SckMail mail = null;
             MailInfo mi =new MailInfo();
             try
             {
                 mail = new SckMail();
                 mi = mi.GetMailInfo();
                 mail.SmtpHost = mi.SmtpHost;
                 mail.Port = mi.Port;
                 mail.Username = mi.From;
                 mail.Password = mi.Password;
                 mailContent = content;
                 mail.SendMail
                 (
                     mi.From,
                     mi.FromName,
                     email,
                     email,
                     SckMail.Prioritys.NORMAL,
                     true,
                     "",
                     CheckStr(title),
                     mailContent
                 );
                 if (mail.ErrorMessage != "")
                 {
                     mailinfo = mail.ErrorMessage;
                 }
             }
             catch (Exception e)
             {
                 mailinfo = e.Message;
             }
             finally
             {
                 mail = null;
             }
             return mailinfo;
         }
         public static string CheckStr(object str)
         {
             string ret = "";
             try
             {
                 if (str == null) ret = "";
                 else
                 {
                     ret = str.ToString();
                     ret = ret.Replace("'", "''");
                 }
             }
             catch
             {
                 ret = "";
             }
             return ret;
         }
     }
     #endregion
 }