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, 0, 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[1024];
            StreamSize = ns.Read(ReadBuffer, 0, ReadBuffer.Length);
            if (StreamSize == 0)
            {
                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, 0, 10) == -1) ? 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 = 1,
            /// <summary>
            /// 默认级别
            /// </summary>
            NORMAL = 3,
            /// <summary>
            /// 最低级别
            /// </summary>
            LOW = 5
        }

        /// <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 = 25;

        /// <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 = { "220", "235", "250", "251", "354", "334", "221" };   // 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, "220"))
                {
                    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 = 0;

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

                    for (int j = 0; j < strResponseCode.Length; j++)
                    {
                        if (smtpcMail.DoesStringContainSMTPCode(strResponseNumber, strResponseCode[j]))
                        {
                            this.strResponse += strResponseNumber;
                            this.strResponse += "<br>";
                            break;
                        }
                        else
                        {
                            if (j == strResponseCode.Length - 1)
                            {
                                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 = 25;    //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 = 25;

        /// <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 = 25;
                }
            }
            catch
            {
                model.Port = 25;
            }
            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
}