C#实现SMTP服务器，使用TCP命令实现，功能比较完善

using System;
using System.Text;
using System.IO;
using System.Net;
using System.Net.Sockets;
using System.Collections;
namespace SkyDev.Web.Mail
{
public enum MailFormat{Text,HTML};
public enum MailPriority{Low=1,Normal=3,High=5};
#region Class mailAttachments
public class MailAttachments
{
private const int MaxAttachmentNum=10;
private IList _Attachments;
public MailAttachments()
{
_Attachments=new ArrayList();
}
public string this[int index]
{
get { return (string)_Attachments[index];}
}
/// <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)
{
//当附件存在时才加入,否则忽略
if (System.IO.File.Exists(filePath))
{
if (_Attachments.Count<MaxAttachmentNum)
{
_Attachments.Add(filePath);
}
}
}
public void Clear()//清除所有附件
{
_Attachments.Clear();
}
public int Count//获取附件个数
{
get { return _Attachments.Count;}
}
}
#endregion//end Class mailAttachments

#region Class MailMessage
/// <summary>
/// MailMessage 表示SMTP要发送的一封邮件的消息。
/// </summary>
public class MailMessage
{
private const int MaxRecipientNum=10;
public MailMessage()
{
_Recipients=new ArrayList();//收件人列表
_Attachments=new MailAttachments();//附件
_BodyFormat=MailFormat.Text;//缺省的邮件格式为Text
_Priority=MailPriority.Normal;
_Charset="GB2312";
}
/// <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;}
}
public string From
{
get{ return _From;}
set { _From=value;}
}
public string FromName
{
get { return _FromName;}
set { _FromName=value;}
}
public string Body
{
get { return _Body;}
set { _Body=value;}
}
public string Subject
{
get { return _Subject;}
set { _Subject=value;}
}
public MailAttachments Attachments
{
get {return _Attachments;}
set { _Attachments=value;}
}
public MailPriority Priority
{
get { return _Priority;}
set { _Priority=value;}
}
public IList Recipients
{
get { return _Recipients;}
}
/// <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)
{
//先检查邮件地址是否符合规范
if (_Recipients.Count<MaxRecipientNum)
{
_Recipients.Add(recipient);//增加到收件人列表
}
}
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]);
}
}
}
public MailFormat BodyFormat
{
set { _BodyFormat=value;}
get { return _BodyFormat;}
}
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 Class SmtpMail
public class SmtpServerHelper
{
private string CRLF="\r\n";//回车换行
/// <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();
public SmtpServerHelper()
{
SMTPCodeAdd();//初始化SMTPCode
}
~SmtpServerHelper()
{
networkStream.Close();
tcpClient.Close();
}
/// <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)
{
//建立文件流对象
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()
{
//[RFC 821 4.2.1.]
/*
4.2.2. NUMERIC ORDER LIST OF REPLY CODES
211 System status, or system help reply
214 Help message
[Information on how to use the receiver or the meaning of a
particular non-standard command; this reply is useful only
to the human user]
220 <domain> Service ready
221 <domain> Service closing transmission channel
250 Requested mail action okay, completed
251 User not local; will forward to <forward-path>

354 Start mail input; end with <CRLF>.<CRLF>

421 <domain> Service not available,
closing transmission channel
[This may be a reply to any command if the service knows it
must shut down]
450 Requested mail action not taken: mailbox unavailable
[E.g., mailbox busy]
451 Requested action aborted: local error in processing
452 Requested action not taken: insufficient system storage

500 Syntax error, command unrecognized
[This may include errors such as command line too long]
501 Syntax error in parameters or arguments
502 Command not implemented
503 Bad sequence of commands
504 Command parameter not implemented
550 Requested action not taken: mailbox unavailable
[E.g., mailbox not found, no access]
551 User not local; please try <forward-path>
552 Requested mail action aborted: exceeded storage allocation
553 Requested action not taken: mailbox name not allowed
[E.g., mailbox syntax incorrect]
554 Transaction failed

*/
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");

/*
211 System status, or system help reply
214 Help message
[Information on how to use the receiver or the meaning of a
particular non-standard command; this reply is useful only
to the human user]
220 <domain> Service ready
221 <domain> Service closing transmission channel
250 Requested mail action okay, completed
251 User not local; will forward to <forward-path>

354 Start mail input; end with <CRLF>.<CRLF>
*/
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;
}
//连接服务器
private bool Connect(string smtpServer,int port)
{
//创建Tcp连接
try
{
tcpClient=new TcpClient(smtpServer,port);
}
catch(Exception e)
{
errmsg=e.ToString();
return false;
}
networkStream=tcpClient.GetStream();
//验证网络连接是否正确
if(RightCodeHT[RecvResponse().Substring(0,3)]==null)
{
errmsg="网络连接失败";
return false;
}
return true;
}
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，SMTP服务器不需要身份验证
/// </summary>
/// <param name="smtpServer"></param>
/// <param name="port"></param>
/// <param name="mailMessage"></param>
/// <returns></returns>
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"></param>
/// <param name="port"></param>
/// <param name="username"></param>
/// <param name="password"></param>
/// <param name="mailMessage"></param>
/// <returns></returns>
public bool SendEmail(string smtpServer,int port,string username,string password,MailMessage mailMessage)
{
return SendEmail(smtpServer,port,false,username,password,mailMessage);
}
private bool SendEmail(string smtpServer,int port,bool ESmtp,string username,string password,MailMessage mailMessage)
{
if (Connect(smtpServer,port)==false)//测试连接服务器是否成功
return false;
string priority=GetPriorityString(mailMessage.Priority);
bool Html=(mailMessage.BodyFormat==MailFormat.HTML);

string[] SendBuffer;
string SendBufferstr;
//进行SMTP验证，现在大部分SMTP服务器都要认证
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
{//不需要身份认证
SendBufferstr="HELO " + smtpServer + CRLF;
if(!Dialog(SendBufferstr,""))
return false;
}
//发件人地址
SendBufferstr="MAIL FROM:<" + mailMessage.From + ">" + 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;
/*
SendBuffer=new string[10];
for(int i=0;i<RecipientBCC.Count;i++)
{
SendBuffer[i]="RCPT TO:<" + RecipientBCC[i].ToString() +">" + CRLF;
}
if(!Dialog(SendBuffer,"密件收件人地址有误"))
return false;
*/
SendBufferstr="DATA" + CRLF;
if(!Dialog(SendBufferstr,""))
return false;
//发件人姓名
SendBufferstr="From:" + mailMessage.FromName + "<" +mailMessage.From +">" +CRLF;
//if(ReplyTo.Trim()!="")
//{
// SendBufferstr+="Reply-To: " + ReplyTo + CRLF;
//}
//SendBufferstr+="To:" + ToName + "<" + Recipient[0] +">" +CRLF;
//至少要有一个收件人
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+="CC:";
//for(int i=0;i<Recipient.Count;i++)
//{
// SendBufferstr+=Recipient[i].ToString() + "<" + Recipient[i].ToString() +">,";
//}
//SendBufferstr+=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;
}

//SendBufferstr += "Content-Transfer-Encoding: base64"+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: application/octet-stream"+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;//内容结束
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;
}
}

public class SmtpMail
{
private static string _SmtpServer;
/// <summary>
/// 格式：SmtpAccount:Password@SmtpServerAddress<br>
/// 或者：SmtpServerAddress<br>
/// <code>
/// SmtpMail.SmtpServer="user:12345678@smtp.126.com";
/// //或者:
/// SmtpMail.SmtpServer="smtp.126.com";
/// 或者：
/// SmtpMail.SmtpServer=SmtpServerHelper.GetSmtpServer("user","12345678","smtp.126.com");
/// </code>
/// </summary>
public static string SmtpServer
{
set { _SmtpServer=value;}
get { return _SmtpServer;}
}
public static bool Send(MailMessage mailMessage,string username,string password)
{
SmtpServerHelper helper=new SmtpServerHelper();
return helper.SendEmail(_SmtpServer,25,username,password,mailMessage);
}
}
#endregion
}

using System;
using NUnit.Framework;
namespace SkyDev.Web.Mail
{
/// <summary>
/// Test 的摘要说明。
/// </summary>
[TestFixture]
public class TestSmtpMail
{
//安装测试用例，完成初始化操作
[SetUp]
public void SetUp()
{
}
//测试结束完成清理操作
[TearDown]
public void TearDown()
{

}

[Test]
public void TestMailAttachments()
{
SkyDev.Web.Mail.MailAttachments attachments=new MailAttachments();
Assert.AreEqual(0,attachments.Count,"初始化MailAttachments");
attachments.Add("c:\\autoexec.bat");
Assert.AreEqual(1,attachments.Count,"增加附件（附件确实存在）");
attachments.Add("c:\\autoexec.dat.txt");
Assert.AreEqual(1,attachments.Count,"增加附件（附件不存在）");
attachments.Clear();
Assert.AreEqual(0,attachments.Count,"清除附件");
}
[Test]
public void TestMailMessage()
{
MailMessage message=new MailMessage();
Assert.AreEqual(0,message.Attachments.Count,"初始化MailAttachments");
Assert.AreEqual(MailFormat.Text,message.BodyFormat,"邮件格式");
Assert.AreEqual("GB2312",message.Charset,"缺省的字符集");
}
[Test]
public void TestSendMail()
{
SmtpMail.SmtpServer="smtp.126.com";
MailMessage mail=new MailMessage();
mail.From="qs1976@126.com";
mail.FromName="曾青松";
mail.AddRecipients(someone@host.com);
mail.Subject="主题：测试邮件";
mail.BodyFormat=MailFormat.Text;
mail.Body="测试的内容.";
mail.Attachments.Add("c:\\test.txt");
SmtpMail.Send(mail,"","");//请填写自己的测试邮件帐号
}
}
}