SmtpServerHelper.cs

using System;
using System.Text;
using System.IO;
using System.Net.Sockets;
using System.Collections;

public enum MailFormat { Text, HTML };
public enum MailPriority { Low = 1, Normal = 3, High = 5 };

/// <summary>
/// 添加附件
/// </summary>
public class MailAttachments
{
    #region 构造函数
    public MailAttachments()
    {
        _Attachments = new ArrayList();
    }
    #endregion

    #region 私有字段
    private IList _Attachments;
    private const int MaxAttachmentNum = 10;
    #endregion

    #region 索引器
    public string this[int index]
    {
        get { return (string)_Attachments[index]; }
    }
    #endregion

    #region 公共方法
    /// <summary>
    /// 添加邮件附件
    /// </summary>
    /// <param name="FilePath">附件的绝对路径</param>
    public void Add(params string[] filePath)
    {
        if (filePath == null)
        {
            throw (new ArgumentNullException("非法的附件"));
        }
        else
        {
            for (int i = 0; i < filePath.Length; i++)
            {
                Add(filePath[i]);
            }
        }
    }

    /// <summary>
    /// 添加一个附件,当指定的附件不存在时，忽略该附件，不产生异常。
    /// </summary>
    /// <param name="filePath">附件的绝对路径</param>
    public void Add(string filePath)
    {
        if (System.IO.File.Exists(filePath))
        {
            if (_Attachments.Count < MaxAttachmentNum)
            {
                _Attachments.Add(filePath);
            }
        }
    }

    /// <summary>
    /// 清除所有附件
    /// </summary>
    public void Clear()
    {
        _Attachments.Clear();
    }

    /// <summary>
    /// 获取附件个数
    /// </summary>
    public int Count
    {
        get { return _Attachments.Count; }
    }
    #endregion
}

/// <summary>
/// 邮件信息
/// </summary>
public class MailMessage
{        
    #region 构造函数
    public MailMessage()
    {
        _Recipients = new ArrayList();        //收件人列表
        _Attachments = new MailAttachments(); //附件
        _BodyFormat = MailFormat.HTML;        //缺省的邮件格式为HTML
        _Priority = MailPriority.Normal;
        _Charset = "GB2312";
    }
    #endregion

    #region 私有字段
    private int _MaxRecipientNum = 30;
    private string _From;      //发件人地址
    private string _FromName;  //发件人姓名
    private IList _Recipients; //收件人
    private MailAttachments _Attachments;//附件
    private string _Body;      //内容
    private string _Subject;   //主题
    private MailFormat _BodyFormat;     //邮件格式
    private string _Charset = "GB2312"; //字符编码格式
    private MailPriority _Priority;     //邮件优先级
    #endregion

    #region 公有属性
    /// <summary>
    /// 设定语言代码，默认设定为GB2312，如不需要可设置为""
    /// </summary>
    public string Charset
    {
        get { return _Charset; }
        set { _Charset = value; }
    }

    /// <summary>
    /// 最大收件人
    /// </summary>
    public int MaxRecipientNum
    {
        get { return _MaxRecipientNum; }
        set { _MaxRecipientNum = value; }
    }

    /// <summary>
    /// 发件人地址
    /// </summary>
    public string From
    {
        get { return _From; }
        set { _From = value; }
    }

    /// <summary>
    /// 发件人姓名
    /// </summary>
    public string FromName
    {
        get { return _FromName; }
        set { _FromName = value; }
    }

    /// <summary>
    /// 内容
    /// </summary>
    public string Body
    {
        get { return _Body; }
        set { _Body = value; }
    }

    /// <summary>
    /// 主题
    /// </summary>
    public string Subject
    {
        get { return _Subject; }
        set { _Subject = value; }
    }

    /// <summary>
    /// 附件
    /// </summary>
    public MailAttachments Attachments
    {
        get { return _Attachments; }
        set { _Attachments = value; }
    }

    /// <summary>
    /// 优先权
    /// </summary>
    public MailPriority Priority
    {
        get { return _Priority; }
        set { _Priority = value; }
    }

    /// <summary>
    /// 收件人
    /// </summary>
    public IList Recipients
    {
        get { return _Recipients; }
    }

    /// <summary>
    /// 邮件格式
    /// </summary>
    public MailFormat BodyFormat
    {
        set { _BodyFormat = value; }
        get { return _BodyFormat; }
    }
    #endregion

    #region 公共方法
    /// <summary>
    /// 增加一个收件人地址
    /// </summary>
    /// <param name="recipient">收件人的Email地址</param>
    public void AddRecipients(string recipient)
    {
        if (_Recipients.Count < MaxRecipientNum)
        {
            _Recipients.Add(recipient);
        }
    }

    /// <summary>
    /// 增加多个收件人地址
    /// </summary>
    /// <param name="recipient">收件人的Email地址集合</param>
    public void AddRecipients(params string[] recipient)
    {
        if (recipient == null)
        {
            throw (new ArgumentException("收件人不能为空."));
        }
        else
        {
            for (int i = 0; i < recipient.Length; i++)
            {
                AddRecipients(recipient[i]);
            }
        }
    }
    #endregion
}

/// <summary>
/// 邮件操作
/// </summary>
public class SmtpServerHelper
{
    #region 构造函数、析构函数
    public SmtpServerHelper()
    {
        SMTPCodeAdd();
    }

    ~SmtpServerHelper()
    {
        networkStream.Close();
        tcpClient.Close();
    }
    #endregion

    #region 私有字段
    /// <summary>
    /// 回车换行
    /// </summary>
    private string CRLF = "\r\n";

    /// <summary>
    /// 错误消息反馈
    /// </summary>
    private string errmsg;

    /// <summary>
    /// TcpClient对象，用于连接服务器
    /// </summary> 
    private TcpClient tcpClient;

    /// <summary>
    /// NetworkStream对象
    /// </summary> 
    private NetworkStream networkStream;

    /// <summary>
    /// 服务器交互记录
    /// </summary>
    private string logs = "";

    /// <summary>
    /// SMTP错误代码哈希表
    /// </summary>
    private Hashtable ErrCodeHT = new Hashtable();

    /// <summary>
    /// SMTP正确代码哈希表
    /// </summary>
    private Hashtable RightCodeHT = new Hashtable();
    #endregion
    
    #region 公有属性
    /// <summary>
    /// 错误消息反馈
    /// </summary>
    public string ErrMsg
    {
        set { errmsg = value; }
        get { return errmsg; }
    }
    #endregion

    #region 私有方法
    /// <summary>
    /// 将字符串编码为Base64字符串
    /// </summary>
    /// <param name="str">要编码的字符串</param>
    private string Base64Encode(string str)
    {
        byte[] barray;
        barray = Encoding.Default.GetBytes(str);
        return Convert.ToBase64String(barray);
    }

    /// <summary>
    /// 将Base64字符串解码为普通字符串
    /// </summary>
    /// <param name="str">要解码的字符串</param>
    private string Base64Decode(string str)
    {
        byte[] barray;
        barray = Convert.FromBase64String(str);
        return Encoding.Default.GetString(barray);
    }

    /// <summary>
    /// 得到上传附件的文件流
    /// </summary>
    /// <param name="FilePath">附件的绝对路径</param>
    private string GetStream(string FilePath)
    {
        System.IO.FileStream FileStr = new System.IO.FileStream(FilePath, System.IO.FileMode.Open);
        byte[] by = new byte[System.Convert.ToInt32(FileStr.Length)];
        FileStr.Read(by, 0, by.Length);
        FileStr.Close();
        return (System.Convert.ToBase64String(by));
    }

    /// <summary>
    /// SMTP回应代码哈希表
    /// </summary>
    private void SMTPCodeAdd()
    {
        ErrCodeHT.Add("421", "服务未就绪，关闭传输信道");
        ErrCodeHT.Add("432", "需要一个密码转换");
        ErrCodeHT.Add("450", "要求的邮件操作未完成，邮箱不可用（例如，邮箱忙）");
        ErrCodeHT.Add("451", "放弃要求的操作；处理过程中出错");
        ErrCodeHT.Add("452", "系统存储不足，要求的操作未执行");
        ErrCodeHT.Add("454", "临时认证失败");
        ErrCodeHT.Add("500", "邮箱地址错误");
        ErrCodeHT.Add("501", "参数格式错误");
        ErrCodeHT.Add("502", "命令不可实现");
        ErrCodeHT.Add("503", "服务器需要SMTP验证");
        ErrCodeHT.Add("504", "命令参数不可实现");
        ErrCodeHT.Add("530", "需要认证");
        ErrCodeHT.Add("534", "认证机制过于简单");
        ErrCodeHT.Add("538", "当前请求的认证机制需要加密");
        ErrCodeHT.Add("550", "要求的邮件操作未完成，邮箱不可用（例如，邮箱未找到，或不可访问）");
        ErrCodeHT.Add("551", "用户非本地，请尝试<forward-path>");
        ErrCodeHT.Add("552", "过量的存储分配，要求的操作未执行");
        ErrCodeHT.Add("553", "邮箱名不可用，要求的操作未执行（例如邮箱格式错误）");
        ErrCodeHT.Add("554", "传输失败");

        RightCodeHT.Add("220", "服务就绪");
        RightCodeHT.Add("221", "服务关闭传输信道");
        RightCodeHT.Add("235", "验证成功");
        RightCodeHT.Add("250", "要求的邮件操作完成");
        RightCodeHT.Add("251", "非本地用户，将转发向<forward-path>");
        RightCodeHT.Add("334", "服务器响应验证Base64字符串");
        RightCodeHT.Add("354", "开始邮件输入，以<CRLF>.<CRLF>结束");
    }

    /// <summary>
    /// 发送SMTP命令
    /// </summary> 
    private bool SendCommand(string str)
    {
        byte[] WriteBuffer;
        if (str == null || str.Trim() == String.Empty)
        {
            return true;
        }
        logs += str;
        WriteBuffer = Encoding.Default.GetBytes(str);
        try
        {
            networkStream.Write(WriteBuffer, 0, WriteBuffer.Length);
        }
        catch
        {
            errmsg = "网络连接错误";
            return false;
        }
        return true;
    }

    /// <summary>
    /// 接收SMTP服务器回应
    /// </summary>
    private string RecvResponse()
    {
        int StreamSize;
        string Returnvalue = String.Empty;
        byte[] ReadBuffer = new byte[1024];
        try
        {
            StreamSize = networkStream.Read(ReadBuffer, 0, ReadBuffer.Length);
        }
        catch
        {
            errmsg = "网络连接错误";
            return "false";
        }

        if (StreamSize == 0)
        {
            return Returnvalue;
        }
        else
        {
            Returnvalue = Encoding.Default.GetString(ReadBuffer).Substring(0, StreamSize);
            logs += Returnvalue + this.CRLF;
            return Returnvalue;
        }
    }

    /// <summary>
    /// 与服务器交互，发送一条命令并接收回应。
    /// </summary>
    /// <param name="str">一个要发送的命令</param>
    /// <param name="errstr">如果错误，要反馈的信息</param>
    private bool Dialog(string str, string errstr)
    {
        if (str == null || str.Trim() == string.Empty)
        {
            return true;
        }
        if (SendCommand(str))
        {
            string RR = RecvResponse();
            if (RR == "false")
            {
                return false;
            }

            //检查返回的代码，根据[RFC 821]返回代码为3位数字代码如220
            string RRCode = RR.Substring(0, 3);
            if (RightCodeHT[RRCode] != null)
            {
                return true;
            }
            else
            {
                if (ErrCodeHT[RRCode] != null)
                {
                    errmsg += (RRCode + ErrCodeHT[RRCode].ToString());
                    errmsg += CRLF;
                }
                else
                {
                    errmsg += RR;
                }
                errmsg += errstr;
                return false;
            }
        }
        else
        {
            return false;
        }
    }

    /// <summary>
    /// 与服务器交互，发送一组命令并接收回应。
    /// </summary>
    private bool Dialog(string[] str, string errstr)
    {
        for (int i = 0; i < str.Length; i++)
        {
            if (!Dialog(str[i], ""))
            {
                errmsg += CRLF;
                errmsg += errstr;
                return false;
            }
        }
        return true;
    }

    /// <summary>
    /// 连接服务器
    /// </summary>
    private bool Connect(string smtpServer, int port)
    {
        try
        {
            tcpClient = new TcpClient(smtpServer, port);
        }
        catch (Exception e)
        {
            errmsg = e.ToString();
            return false;
        }
        networkStream = tcpClient.GetStream();

        if (RightCodeHT[RecvResponse().Substring(0, 3)] == null)
        {
            errmsg = "网络连接失败";
            return false;
        }
        return true;
    }

    /// <summary>
    /// 获取优先级
    /// </summary>
    /// <param name="mailPriority">优先级</param>
    private string GetPriorityString(MailPriority mailPriority)
    {
        string priority = "Normal";
        if (mailPriority == MailPriority.Low)
        {
            priority = "Low";
        }
        else if (mailPriority == MailPriority.High)
        {
            priority = "High";
        }
        return priority;
    }

    /// <summary>
    /// 发送电子邮件
    /// </summary>
    /// <param name="smtpServer">发信SMTP服务器</param>
    /// <param name="port">端口，默认为25</param>
    /// <param name="username">发信人邮箱地址</param>
    /// <param name="password">发信人邮箱密码</param>
    /// <param name="mailMessage">邮件内容</param>
    private bool SendEmail(string smtpServer, int port, bool ESmtp, string username, string password, MailMessage mailMessage)
    {
        if (Connect(smtpServer, port) == false) return false;

        string priority = GetPriorityString(mailMessage.Priority);

        bool Html = (mailMessage.BodyFormat == MailFormat.HTML);

        string[] SendBuffer;
        string SendBufferstr;

        //进行SMTP验证
        if (ESmtp)
        {
            SendBuffer = new String[4];
            SendBuffer[0] = "EHLO " + smtpServer + CRLF;
            SendBuffer[1] = "AUTH LOGIN" + CRLF;
            SendBuffer[2] = Base64Encode(username) + CRLF;
            SendBuffer[3] = Base64Encode(password) + CRLF;
            if (!Dialog(SendBuffer, "SMTP服务器验证失败，请核对用户名和密码。")) return false;
        }
        else
        {
            SendBufferstr = "HELO " + smtpServer + CRLF;
            if (!Dialog(SendBufferstr, "")) return false;
        }

        //发件人地址
        SendBufferstr = "MAIL FROM:<" + username + ">" + CRLF;
        if (!Dialog(SendBufferstr, "发件人地址错误，或不能为空")) return false;

        //收件人地址
        SendBuffer = new string[mailMessage.Recipients.Count];
        for (int i = 0; i < mailMessage.Recipients.Count; i++)
        {
            SendBuffer[i] = "RCPT TO:<" + (string)mailMessage.Recipients[i] + ">" + CRLF;
        }
        if (!Dialog(SendBuffer, "收件人地址有误")) return false;

        SendBufferstr = "DATA" + CRLF;
        if (!Dialog(SendBufferstr, "")) return false;

        //发件人姓名
        SendBufferstr = "From:" + mailMessage.FromName + "<" + mailMessage.From + ">" + CRLF;

        if (mailMessage.Recipients.Count == 0)
        {
            return false;
        }
        else
        {
            SendBufferstr += "To:=?" + mailMessage.Charset.ToUpper() + "?B?" + Base64Encode((string)mailMessage.Recipients[0]) + "?=" + "<" + (string)mailMessage.Recipients[0] + ">" + CRLF;
        }
        SendBufferstr += ((mailMessage.Subject == String.Empty || mailMessage.Subject == null) ? "Subject:" : ((mailMessage.Charset == "") ? ("Subject:" + mailMessage.Subject) : ("Subject:" + "=?" + mailMessage.Charset.ToUpper() + "?B?" + Base64Encode(mailMessage.Subject) + "?="))) + CRLF;
        SendBufferstr += "X-Priority:" + priority + CRLF;
        SendBufferstr += "X-MSMail-Priority:" + priority + CRLF;
        SendBufferstr += "Importance:" + priority + CRLF;
        SendBufferstr += "X-Mailer: Lion.Web.Mail.SmtpMail Pubclass [cn]" + CRLF;
        SendBufferstr += "MIME-Version: 1.0" + CRLF;
        if (mailMessage.Attachments.Count != 0)
        {
            SendBufferstr += "Content-Type: multipart/mixed;" + CRLF;
            SendBufferstr += " boundary=\"=====" + (Html ? "001_Dragon520636771063_" : "001_Dragon303406132050_") + "=====\"" + CRLF + CRLF;
        }
        if (Html)
        {
            if (mailMessage.Attachments.Count == 0)
            {
                SendBufferstr += "Content-Type: multipart/alternative;" + CRLF; //内容格式和分隔符
                SendBufferstr += " boundary=\"=====003_Dragon520636771063_=====\"" + CRLF + CRLF;
                SendBufferstr += "This is a multi-part message in MIME format." + CRLF + CRLF;
            }
            else
            {
                SendBufferstr += "This is a multi-part message in MIME format." + CRLF + CRLF;
                SendBufferstr += "--=====001_Dragon520636771063_=====" + CRLF;
                SendBufferstr += "Content-Type: multipart/alternative;" + CRLF; //内容格式和分隔符
                SendBufferstr += " boundary=\"=====003_Dragon520636771063_=====\"" + CRLF + CRLF;
            }
            SendBufferstr += "--=====003_Dragon520636771063_=====" + CRLF;
            SendBufferstr += "Content-Type: text/plain;" + CRLF;
            SendBufferstr += ((mailMessage.Charset == "") ? (" charset=\"iso-8859-1\"") : (" charset=\"" + mailMessage.Charset.ToLower() + "\"")) + CRLF;
            SendBufferstr += "Content-Transfer-Encoding: base64" + CRLF + CRLF;
            SendBufferstr += Base64Encode("邮件内容为HTML格式，请选择HTML方式查看") + CRLF + CRLF;

            SendBufferstr += "--=====003_Dragon520636771063_=====" + CRLF;

            SendBufferstr += "Content-Type: text/html;" + CRLF;
            SendBufferstr += ((mailMessage.Charset == "") ? (" charset=\"iso-8859-1\"") : (" charset=\"" + mailMessage.Charset.ToLower() + "\"")) + CRLF;
            SendBufferstr += "Content-Transfer-Encoding: base64" + CRLF + CRLF;
            SendBufferstr += Base64Encode(mailMessage.Body) + CRLF + CRLF;
            SendBufferstr += "--=====003_Dragon520636771063_=====--" + CRLF;
        }
        else
        {
            if (mailMessage.Attachments.Count != 0)
            {
                SendBufferstr += "--=====001_Dragon303406132050_=====" + CRLF;
            }
            SendBufferstr += "Content-Type: text/plain;" + CRLF;
            SendBufferstr += ((mailMessage.Charset == "") ? (" charset=\"iso-8859-1\"") : (" charset=\"" + mailMessage.Charset.ToLower() + "\"")) + CRLF;
            SendBufferstr += "Content-Transfer-Encoding: base64" + CRLF + CRLF;
            SendBufferstr += Base64Encode(mailMessage.Body) + CRLF;
        }
        if (mailMessage.Attachments.Count != 0)
        {
            for (int i = 0; i < mailMessage.Attachments.Count; i++)
            {
                string filepath = (string)mailMessage.Attachments[i];
                SendBufferstr += "--=====" + (Html ? "001_Dragon520636771063_" : "001_Dragon303406132050_") + "=====" + CRLF;
                SendBufferstr += "Content-Type: text/plain;" + CRLF;
                SendBufferstr += " name=\"=?" + mailMessage.Charset.ToUpper() + "?B?" + Base64Encode(filepath.Substring(filepath.LastIndexOf("\\") + 1)) + "?=\"" + CRLF;
                SendBufferstr += "Content-Transfer-Encoding: base64" + CRLF;
                SendBufferstr += "Content-Disposition: attachment;" + CRLF;
                SendBufferstr += " filename=\"=?" + mailMessage.Charset.ToUpper() + "?B?" + Base64Encode(filepath.Substring(filepath.LastIndexOf("\\") + 1)) + "?=\"" + CRLF + CRLF;
                SendBufferstr += GetStream(filepath) + CRLF + CRLF;
            }
            SendBufferstr += "--=====" + (Html ? "001_Dragon520636771063_" : "001_Dragon303406132050_") + "=====--" + CRLF + CRLF;
        }
        SendBufferstr += CRLF + "." + CRLF;
        if (!Dialog(SendBufferstr, "错误信件信息")) return false;

        SendBufferstr = "QUIT" + CRLF;
        if (!Dialog(SendBufferstr, "断开连接时错误")) return false;

        networkStream.Close();
        tcpClient.Close();
        return true;
    }
    #endregion

    #region 公有方法
    /// <summary>
    /// 发送电子邮件,SMTP服务器不需要身份验证
    /// </summary>
    /// <param name="smtpServer">发信SMTP服务器</param>
    /// <param name="port">端口，默认为25</param>
    /// <param name="mailMessage">邮件内容</param>
    public bool SendEmail(string smtpServer, int port, MailMessage mailMessage)
    {
        return SendEmail(smtpServer, port, false, "", "", mailMessage);
    }

    /// <summary>
    /// 发送电子邮件,SMTP服务器需要身份验证
    /// </summary>
    /// <param name="smtpServer">发信SMTP服务器</param>
    /// <param name="port">端口，默认为25</param>
    /// <param name="username">发信人邮箱地址</param>
    /// <param name="password">发信人邮箱密码</param>
    /// <param name="mailMessage">邮件内容</param>
    public bool SendEmail(string smtpServer, int port, string username, string password, MailMessage mailMessage)
    {
        return SendEmail(smtpServer, port, true, username, password, mailMessage);
    }
    #endregion
}

/// <summary>
/// 发送邮件
/// </summary>
//--------------------调用-----------------------
//MailAttachments ma=new MailAttachments();
//ma.Add(@"附件地址");
//MailMessage mail = new MailMessage();
//mail.Attachments=ma;
//mail.Body="你好";
//mail.AddRecipients("zjy99684268@163.com");
//mail.From="zjy99684268@163.com";
//mail.FromName="zjy";
//mail.Subject="Hello";
//SmtpClient sp = new SmtpClient();
//sp.SmtpServer = "smtp.163.com";
//sp.Send(mail, "zjy99684268@163.com", "123456");
//------------------------------------------------
public class SmtpClient
{
    #region 构造函数
    public SmtpClient()
    {}

    public SmtpClient(string _smtpServer)
    {
        _SmtpServer = _smtpServer;
    }
    #endregion

    #region 私有字段
    private string errmsg;
    private string _SmtpServer;
    #endregion

    #region 公有属性
    /// <summary>
    /// 错误消息反馈
    /// </summary>
    public string ErrMsg
    {
        get { return errmsg; }
    }

    /// <summary>
    /// 邮件服务器
    /// </summary>
    public string SmtpServer
    {
        set { _SmtpServer = value; }
        get { return _SmtpServer; }
    }
    #endregion

    public bool Send(MailMessage mailMessage, string username, string password)
    {
        SmtpServerHelper helper = new SmtpServerHelper();
        if (helper.SendEmail(_SmtpServer, 25, username, password, mailMessage))
            return true;
        else
        {
            errmsg = helper.ErrMsg;
            return false;
        }
    }
}

/// <summary>
/// 操作服务器上邮件
/// </summary>
public class SmtpMail
{
    public SmtpMail()
    { }

    #region 字段
    private StreamReader sr;
    private StreamWriter sw;
    private TcpClient tcpClient;
    private NetworkStream networkStream;
    #endregion

    #region 私有方法
    /// <summary>
    /// 向服务器发送信息
    /// </summary>
    private bool SendDataToServer(string str)
    {
        try
        {
            sw.WriteLine(str);
            sw.Flush();
            return true;
        }
        catch (Exception err)
        {
            return false;
        }
    }

    /// <summary>
    /// 从网络流中读取服务器回送的信息
    /// </summary>
    private string ReadDataFromServer()
    {
        string str = null;
        try
        {
            str = sr.ReadLine();
            if (str[0] == '-')
            {
                str = null;
            }
        }
        catch (Exception err)
        {
            str = err.Message;
        }
        return str;
    }
    #endregion

    #region 获取邮件信息
    /// <summary>
    /// 获取邮件信息
    /// </summary>
    /// <param name="uid">邮箱账号</param>
    /// <param name="pwd">邮箱密码</param>
    /// <returns>邮件信息</returns>
    public ArrayList ReceiveMail(string uid, string pwd)
    {
        ArrayList EmailMes = new ArrayList();
        string str;
        int index = uid.IndexOf('@');
        string pop3Server = "pop3." + uid.Substring(index + 1);
        tcpClient = new TcpClient(pop3Server, 110);
        networkStream = tcpClient.GetStream();
        sr = new StreamReader(networkStream);
        sw = new StreamWriter(networkStream);

        if (ReadDataFromServer() == null) return EmailMes;
        if (SendDataToServer("USER " + uid) == false) return EmailMes;
        if (ReadDataFromServer() == null) return EmailMes;
        if (SendDataToServer("PASS " + pwd) == false) return EmailMes;
        if (ReadDataFromServer() == null) return EmailMes;
        if (SendDataToServer("LIST") == false) return EmailMes;
        if ((str = ReadDataFromServer()) == null) return EmailMes;

        string[] splitString = str.Split(' ');
        int count = int.Parse(splitString[1]);
        if (count > 0)
        {
            for (int i = 0; i < count; i++)
            {
                if ((str = ReadDataFromServer()) == null) return EmailMes;
                splitString = str.Split(' ');
                EmailMes.Add(string.Format("第{0}封邮件，{1}字节", splitString[0], splitString[1]));
            }
            return EmailMes;
        }
        else
        {
            return EmailMes;
        }
    }
    #endregion

    #region 读取邮件内容
    /// <summary>
    /// 读取邮件内容
    /// </summary>
    /// <param name="mailMessage">第几封</param>
    /// <returns>内容</returns>
    public string ReadEmail(string str)
    {
        string state = "";
        if (SendDataToServer("RETR " + str) == false)
            state = "Error";
        else
        {
            state = sr.ReadToEnd();
        }
        return state;
    }
    #endregion

    #region 删除邮件
    /// <summary>
    /// 删除邮件
    /// </summary>
    /// <param name="str">第几封</param>
    /// <returns>操作信息</returns>
    public string DeleteEmail(string str)
    {
        string state = "";
        if (SendDataToServer("DELE " + str) == true)
        {
            state = "成功删除";
        }
        else
        {
            state = "Error";
        }
        return state;
    }
    #endregion

    #region 关闭服务器连接
    /// <summary>
    /// 关闭服务器连接
    /// </summary>
    public void CloseConnection()
    {
        SendDataToServer("QUIT");
        sr.Close();
        sw.Close();
        networkStream.Close();
        tcpClient.Close();
    }
    #endregion
}