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:[e-mail]"; 
/// //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="[e-mail]"; 
mail.FromName="曾青松"; 
mail.AddRecipients("[e-mail]"); 
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 
} 
} 
}