由于工作需要,查阅了相关资料,利用VC2005实现了邮件发送,源程序如下:

//-------------------------------------------------------SmtpSendEmail.h------------------------------------

#pragma once
#include <list>
#include <string>
#include <fstream>
#include<WinSock2.h>
#pragma comment(lib, "ws2_32.lib")
using namespace std;

#ifndef _SMTPSENDEMAIL_H
#define _SMTPSENDEMAIL_H

//发送线程
DWORD WINAPI SendMailThread(LPVOID lpParam);

class SmtpSendEmail
{
public:
SmtpSendEmail(void);
virtual ~SmtpSendEmail(void);

public:
void SetPost( int nPost );
void SetHost( string strHost );
void SetAccount( string strAccount );
void SetPassword( string strPassword );
void SetMailFrom( string strMailFrom );
void SetSendTo( string strSendTo );
void SetSubject( string strSubject );
void SetDateTime( string strDateTime );
bool AddDataFromString( string strData );
bool AddDataFromBuffer( char* szData, int iLen );
bool AddDataFromFile( string strFileName );
bool AddAttachedFile( string strFilePath, string strFileName );
bool SandThread();
bool StarMailThread();

private:
int Base64EncodeLen( int nSrcLen );
bool Base64Encode( const BYTE* szSrcData, int nSrcLen, BYTE* szDestData, int* pnDestLen );
bool CheckResponse(int nResCode);
bool ConnectServ();
bool SendHelo();
bool SendEhlo();
bool AutoLogin();
bool EmailFrom();
bool EmailTo();
bool DataServ();
bool SendData();
bool SendAttachedFile();
bool QuitServ();

private:
    static const char   m_szBase64CodeTable[];
    static const string MIMEMultipartMixedLogin;
    static const string MIMETextPlainLogin;
    static const string MyBoundary;
    static const string CTCodeQP;
    static const string CTCodeBase64;
    static const string CTTextPlainCharCodeGB2312;
    static const string CTAppOctetStreamName;
    static const string CDAttachemntFileName;

    struct SMTPSTRU
    {
        int    nPost;
        string strHost;
        string strAccount;
        string strPassword;
        string strMailFrom;
        string strSendTo;
        string strSubject;
        string strDateTime;
        string strData;
    };
    struct FILEINFOSTRU
    {
        string strPath;
        string strFile;
    };

SOCKET             m_hSocket;
    SMTPSTRU           m_smtpPro;
    list<FILEINFOSTRU> m_listFileInfo;
};

#endif

//------------------------------------------------SmtpSendEmail.cpp------------------------------------------------------

#include "StdAfx.h"
#include "SmtpSendEmail.h"

//发送线程
DWORD WINAPI SendMailThread(LPVOID lpParam)
{
((SmtpSendEmail*)lpParam)->SandThread();
return 0;
}

const char SmtpSendEmail::m_szBase64CodeTable[]       = { "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/" };
const string SmtpSendEmail::MIMEMultipartMixedLogin   = "X-Mailer: Gddsky mailer/r/n MIME-Version: 1.0/r/nContent-type: multipart/mixed;boundary=/"===_000_Gddsky_000_===/"/r/n/r/n";
const string SmtpSendEmail::MIMETextPlainLogin        = "X-Mailer: Gddsky mailer/r/nMIME-Version: 1.0/r/nContent-type: text/plain;charset=/"GB2312/"/r/n Content-Transfer-Encoding: base64/r/n/r/n";
const string SmtpSendEmail::MyBoundary                = "/r/n--===_000_Gddsky_000_===/r/n";
const string SmtpSendEmail::CTCodeQP                  = "Content-Transfer-Encoding: quoted-printable/r/n/r/n";
const string SmtpSendEmail::CTCodeBase64              = "Content-Transfer-Encoding: base64/r/n/r/n";
const string SmtpSendEmail::CTTextPlainCharCodeGB2312 = "Content-Type: text/plain;charset=/"GB2312/"/r/n";
const string SmtpSendEmail::CTAppOctetStreamName      = "Content-Type: application/octet-stream;name=";
const string SmtpSendEmail::CDAttachemntFileName      = "Content-Disposition: attachment;filename=";

SmtpSendEmail::SmtpSendEmail(void)
{
WSADATA wsaData = {0};
WORD wVersionRequested = MAKEWORD( 2, 2 );
WSAStartup( wVersionRequested, &wsaData );
     m_smtpPro.nPost = 25;
m_hSocket = 0;
}

SmtpSendEmail::~SmtpSendEmail(void)
{
     m_listFileInfo.clear();
//关闭SOCK
closesocket(m_hSocket);
m_hSocket = 0;
WSACleanup();
}

int SmtpSendEmail::Base64EncodeLen( int nSrcLen )
{
int nRet = nSrcLen * 4 / 3 + nSrcLen % 3;
    int nCRLFs = ( nRet / 76 + 1 ) * 2;
    int nOnLastLine = nRet % 76;
    nRet += nCRLFs;
    if( nOnLastLine && nOnLastLine % 4 )
    {
        nRet += 4 - ( nOnLastLine % 4 );
    }
    return nRet;
}

bool SmtpSendEmail::Base64Encode( const BYTE* szSrcData, int nSrcLen, BYTE* szDestData, int* pnDestLen )
{
if( !( szSrcData && nSrcLen && szDestData && pnDestLen && *pnDestLen ) )
{
   return false;
}

if( *pnDestLen < Base64EncodeLen( nSrcLen ) )
{
   return false;
}

int nWritten = 0 ;
int nLen1 = ( nSrcLen / 3 ) * 4;
int nLen2 = nLen1 / 76;
int nLen3 = 19;

for( int i = 0; i <= nLen2; i++ )
{
   if( i == nLen2 )
   {
    nLen3 = ( nLen1 % 76 ) / 4;
   }
   for( int j = 0; j < nLen3; j++ )
   {
    DWORD dwCurr = 0;
    for( int n = 0; n < 3; n++ )
    {
     dwCurr |= *szSrcData++;
     dwCurr <<= 8;
    }
    for( int k = 0; k < 4; k++ )
    {
     BYTE b = ( BYTE )( dwCurr >> 26 );
                *szDestData++ = m_szBase64CodeTable[ b ];
                dwCurr <<= 6;
    }
   }
   nWritten += nLen3 * 4;

   *szDestData++ = '/r';
   *szDestData++ = '/n';
   nWritten+= 2;
}

if( nWritten )
{
   szDestData-= 2;
   nWritten -= 2;
}

nLen2 = ( nSrcLen % 3 ) ? ( nSrcLen % 3 ) + 1 : 0;
if( nLen2 )
{
   DWORD dwCurr = 0;
   for( int n = 0; n < 3; n++ )
   {
    if( n < ( nSrcLen % 3 ) )
    {
     dwCurr |= *szSrcData++;
    }
    dwCurr <<= 8;
   }
   for( int k = 0; k < nLen2; k++ )
   {
    BYTE b = ( BYTE ) ( dwCurr >> 26 );
            *szDestData++ = m_szBase64CodeTable[ b ];
            dwCurr <<= 6;
   }
   nWritten += nLen2;

   nLen3 = nLen2 ? 4 - nLen2 : 0;
   for( int j = 0; j < nLen3; j++ )
   {
    *szDestData++ = '=';
   }
   nWritten += nLen3;
}
*pnDestLen = nWritten;

return true;
}

void SmtpSendEmail::SetPost( int nPost )
{
m_smtpPro.nPost = nPost;
}

void SmtpSendEmail::SetHost( string strHost )
{
m_smtpPro.strHost = strHost;
}

void SmtpSendEmail::SetAccount( string strAccount )
{
m_smtpPro.strAccount = strAccount;
}

void SmtpSendEmail::SetPassword( string strPassword )
{
m_smtpPro.strPassword = strPassword;
}

void SmtpSendEmail::SetMailFrom( string strMailFrom )
{
m_smtpPro.strMailFrom = strMailFrom;
}

void SmtpSendEmail::SetSendTo( string strSendTo )
{
m_smtpPro.strSendTo = strSendTo;   
}

void SmtpSendEmail::SetSubject( string strSubject )
{
m_smtpPro.strSubject = strSubject;  
}

void SmtpSendEmail::SetDateTime( string strDateTime )
{
m_smtpPro.strDateTime = strDateTime;
}

bool SmtpSendEmail::AddDataFromString( std::string strData )
{
m_smtpPro.strData.append( strData.c_str() );
return true;
}

bool SmtpSendEmail::AddDataFromBuffer( char* szData, int iLen )
{
if( NULL != szData && iLen > 0)
{
   m_smtpPro.strData.append( szData, iLen );
   return true;
}

return false;
}

bool SmtpSendEmail::AddDataFromFile( string strFileName )
{
ifstream InputFile;
InputFile.open( strFileName.c_str(), ios_base::binary | ios_base::in );
if( InputFile.fail() )
{
   return false;
}
InputFile.seekg( 0, ios_base::end );
int iLen = InputFile.tellg();
InputFile.seekg( 0, ios_base::beg );

char* pszFileData = new char[iLen + 1];
memset(pszFileData, 0, iLen + 1);
InputFile.read( pszFileData, iLen );
m_smtpPro.strData.append( pszFileData );
delete pszFileData;

return true;
}

bool SmtpSendEmail::AddAttachedFile(string strFilePath, string strFileName)
{
FILEINFOSTRU fileInfo;
fileInfo.strPath = strFilePath;
fileInfo.strFile = strFileName;
m_listFileInfo.push_back(fileInfo);
return true;
}

bool SmtpSendEmail::StarMailThread()
{
DWORD threadID;
HANDLE threadHandle = CreateThread(0, 0, SendMailThread, this, 0, &threadID);
return true;
}

// 发送邮件
bool SmtpSendEmail::SandThread()
{
//创建SOCK，连接服务器
if (!ConnectServ())
{
   return false;
}
    //HELO CMD
if(!SendHelo())
{
   return false;
}
//EHLO CMD
if (SendEhlo())
{
   if (!AutoLogin())
   {
    return false;
   }
}
//MAIL FORM CMD
if (!EmailFrom())
{
   return false;
}
//RCPT TO CMD
if (!EmailTo())
{
   return false;
}
//DATA CMD
if (!DataServ())
{
   return false;
}
// 邮件内容
if (m_listFileInfo.size() > 0)
{
   if (!SendAttachedFile())
   {
    return false;
   }
}
else
{
   if (!SendData())
   {
    return false;
   }
}

// 发送结束
if (!QuitServ())
{
   return false;
}

//关闭SOCK
closesocket(m_hSocket);
m_hSocket = 0;

    return true;
}

bool SmtpSendEmail::ConnectServ()
{
//创建SOCK
m_hSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);

//超时
struct timeval timeoutRecv = {0};
timeoutRecv.tv_sec = 30000;
setsockopt(m_hSocket, SOL_SOCKET, SO_RCVTIMEO, (const char *)&timeoutRecv, sizeof(timeoutRecv));

//连接
LPHOSTENT pHost = gethostbyname(m_smtpPro.strHost.c_str());
struct sockaddr_in servAddr;
servAddr.sin_family = AF_INET;
servAddr.sin_addr.s_addr = *(ULONG *)pHost->h_addr_list[0];
servAddr.sin_port = htons(25);
if (connect(m_hSocket, (const struct sockaddr *)&servAddr, sizeof(struct sockaddr_in)) == SOCKET_ERROR)
{
   closesocket(m_hSocket);
   m_hSocket = 0;
   return false;
}

return CheckResponse(220);
}

bool SmtpSendEmail::CheckResponse(int nResCode)
{
char szRecvBuf[1024] = {0};
char szTemp[20] = {0};
_itoa_s(nResCode, szTemp, 20, 10);
//接收回复
int nRecvLen = recv(m_hSocket, szRecvBuf, 1024, 0);
if (nRecvLen <= 0)
{
   closesocket(m_hSocket);
   m_hSocket = 0;
   return false;
}

if (nRecvLen >= (int)strlen(szTemp))
{
   if (strstr(szRecvBuf, szTemp) != NULL)
   {
    return true;
   }
}
return false;
}

bool SmtpSendEmail::SendHelo()
{
string strSendBuf;
strSendBuf.append( "HELO " );
strSendBuf.append(m_smtpPro.strHost.c_str());
strSendBuf.append("/r/n");
//发送
int nSendLen = send(m_hSocket, strSendBuf.c_str(), (int)strSendBuf.size(), 0);
if (nSendLen != (int)strSendBuf.size())
{
   closesocket(m_hSocket);
   m_hSocket = 0;
   return false;
}

//回复
return CheckResponse(250);
}

bool SmtpSendEmail::SendEhlo()
{
string strSendBuf;
strSendBuf.append( "EHLO 126.com /r/n" );
//strSendBuf.append(m_smtpPro.Host.c_str());
//strSendBuf.append("/r/n");
//发送
int nSendLen = send(m_hSocket, strSendBuf.c_str(), (int)strSendBuf.size(), 0);
if (nSendLen != (int)strSendBuf.size())
{
   closesocket(m_hSocket);
   m_hSocket = 0;
   return false;
}

//回复
return CheckResponse(250);
}

bool SmtpSendEmail::AutoLogin()
{
int nTemp = 1024;
char szBaseBuf[1024] = {0};
string strSendBuf;
strSendBuf.append( "AUTH LOGIN/r/n" );
//发送
int nSendLen = send(m_hSocket, strSendBuf.c_str(), (int)strSendBuf.size(), 0);
if (nSendLen != (int)strSendBuf.size())
{
   closesocket(m_hSocket);
   m_hSocket = 0;
   return false;
}
//回复
if (!CheckResponse(334))
{
   return false;
}

//帐户
strSendBuf.clear();
Base64Encode( (const BYTE*)m_smtpPro.strAccount.c_str(), (int)m_smtpPro.strAccount.size(), (BYTE*)szBaseBuf, &nTemp );
strSendBuf.append( szBaseBuf );
//发送
nSendLen = send(m_hSocket, strSendBuf.c_str(), (int)strSendBuf.size(), 0);
if (nSendLen != (int)strSendBuf.size())
{
   closesocket(m_hSocket);
   m_hSocket = 0;
   return false;
}
//回复
if (!CheckResponse(334))
{
   return false;
}

//密码
strSendBuf.clear();
nTemp = 1024;
memset(szBaseBuf, 0, 1024 );
Base64Encode( (const BYTE*)m_smtpPro.strPassword.c_str(), (int)m_smtpPro.strPassword.size(), (BYTE*)szBaseBuf, &nTemp );
strSendBuf.append( szBaseBuf );
//发送
nSendLen = send(m_hSocket, strSendBuf.c_str(), (int)strSendBuf.size(), 0);
if (nSendLen != (int)strSendBuf.size())
{
   closesocket(m_hSocket);
   m_hSocket = 0;
   return false;
}

//回复
return CheckResponse(235);
}

bool SmtpSendEmail::EmailFrom()
{
string strSendBuf;
strSendBuf.append( "MAIL FROM: <" );
strSendBuf.append( m_smtpPro.strMailFrom.c_str() );
strSendBuf.append( ">/r/n" );
//发送
int nSendLen = send(m_hSocket, strSendBuf.c_str(), (int)strSendBuf.size(), 0);
if (nSendLen != (int)strSendBuf.size())
{
   closesocket(m_hSocket);
   m_hSocket = 0;
   return false;
}

//回复
return CheckResponse(250);
}

bool SmtpSendEmail::EmailTo()
{
string strSendBuf;
strSendBuf.append( "RCPT TO: <" );
strSendBuf.append( m_smtpPro.strSendTo.c_str() );
strSendBuf.append( ">/r/n" );
//发送
int nSendLen = send(m_hSocket, strSendBuf.c_str(), (int)strSendBuf.size(), 0);
if (nSendLen != (int)strSendBuf.size())
{
   closesocket(m_hSocket);
   m_hSocket = 0;
   return false;
}

//回复
return CheckResponse(250);
}

bool SmtpSendEmail::DataServ()
{
string strSendBuf;
strSendBuf.append( "DATA/r/n" );
//发送
int nSendLen = send(m_hSocket, strSendBuf.c_str(), (int)strSendBuf.size(), 0);
if (nSendLen != (int)strSendBuf.size())
{
   closesocket(m_hSocket);
   m_hSocket = 0;
   return false;
}

//回复
return CheckResponse(354);
}
bool SmtpSendEmail::SendData()
{
string strSendBuf;
strSendBuf.append( "From: <" );
strSendBuf.append( m_smtpPro.strMailFrom.c_str() );
strSendBuf.append( ">/r/n" );

strSendBuf.append( "To: <" );
strSendBuf.append( m_smtpPro.strSendTo.c_str() );
strSendBuf.append( ">/r/n" );

strSendBuf.append( "Date: " );
strSendBuf.append( m_smtpPro.strDateTime.c_str() );
strSendBuf.append( "/r/n" );

strSendBuf.append( "Subject: " );
strSendBuf.append( m_smtpPro.strSubject.c_str() );
strSendBuf.append( "/r/n" );

strSendBuf.append( MIMETextPlainLogin.c_str() );

//内容
strSendBuf.append(m_smtpPro.strData.c_str());
//结束符
strSendBuf.append("/r/n./r/n");
//发送
int nSendLen = send(m_hSocket, strSendBuf.c_str(), (int)strSendBuf.size(), 0);
if (nSendLen != (int)strSendBuf.size())
{
   closesocket(m_hSocket);
   m_hSocket = 0;
   return false;
}

//回复
return CheckResponse(250);
}

bool SmtpSendEmail::SendAttachedFile()
{
string strSendBuf;
strSendBuf.append( "From: <" );
strSendBuf.append( m_smtpPro.strMailFrom.c_str() );
strSendBuf.append( ">/r/n" );

strSendBuf.append( "To: <" );
strSendBuf.append( m_smtpPro.strSendTo.c_str() );
strSendBuf.append( ">/r/n" );

strSendBuf.append( "Date: " );
strSendBuf.append( m_smtpPro.strDateTime.c_str() );
strSendBuf.append( "/r/n" );

strSendBuf.append( "Subject: " );
strSendBuf.append( m_smtpPro.strSubject.c_str() );
strSendBuf.append( "/r/n" );

strSendBuf.append( MIMEMultipartMixedLogin.c_str() );

strSendBuf.append( MyBoundary.c_str() );
strSendBuf.append( CTTextPlainCharCodeGB2312.c_str() );
strSendBuf.append( CTCodeBase64.c_str() );
//内容加密
int nSize = Base64EncodeLen( (int)m_smtpPro.strData.size() );
BYTE *pszDataBuf = new BYTE[nSize+1];
memset(pszDataBuf, 0, nSize+1);
Base64Encode( (const BYTE*)m_smtpPro.strData.c_str(), (int)m_smtpPro.strData.size(), (BYTE*)pszDataBuf, &nSize );
strSendBuf.append((char*)pszDataBuf);
delete pszDataBuf;
//发送
int nSendLen = send(m_hSocket, strSendBuf.c_str(), (int)strSendBuf.size(), 0);
if (nSendLen != (int)strSendBuf.size())
{
   closesocket(m_hSocket);
   m_hSocket = 0;
   return false;
}
//附件
for( list<FILEINFOSTRU>::iterator it = m_listFileInfo.begin(); it != m_listFileInfo.end(); it++ )
{
   string strFile = ( *it ).strPath + ( *it ).strFile;
   string strFileData;
   // 读文件
   ifstream InputFile;
   InputFile.open( strFile.c_str(), ios_base::binary | ios_base::in );
   if( InputFile.fail() )
   {
    continue;
   }
   InputFile.seekg( 0, ios_base::end );
   int iLen = InputFile.tellg();
   InputFile.seekg( 0, ios_base::beg );

   strFileData.resize( iLen );
   InputFile.read( (char*)strFileData.c_str(), iLen );

   // 加入一个附件头
   strSendBuf.clear();
   strSendBuf.append( MyBoundary.c_str() );
   strSendBuf.append( CTAppOctetStreamName.c_str() );
   strSendBuf.append( ( *it ).strFile.c_str() );
   strSendBuf.append( "/r/n" );
   strSendBuf.append( CDAttachemntFileName.c_str() );
   strSendBuf.append( ( *it ).strFile.c_str() );
   strSendBuf.append( "/r/n" );
   strSendBuf.append( CTCodeBase64.c_str() );
   //内容加密
   nSize = Base64EncodeLen( (int)strFileData.size() );
   pszDataBuf = new BYTE[nSize+1];
   memset(pszDataBuf, 0, nSize+1);
   Base64Encode( (const BYTE*)strFileData.c_str(), (int)strFileData.size(), (BYTE*)pszDataBuf, &nSize );
   strSendBuf.append((char*)pszDataBuf);
   delete pszDataBuf;
   //发送
   nSendLen = send(m_hSocket, strSendBuf.c_str(), (int)strSendBuf.size(), 0);
   if (nSendLen != (int)strSendBuf.size())
   {
    closesocket(m_hSocket);
    m_hSocket = 0;
    return false;
   }
}
//结束符
strSendBuf.clear();
strSendBuf.append("/r/n./r/n");
//发送
nSendLen = send(m_hSocket, strSendBuf.c_str(), (int)strSendBuf.size(), 0);
if (nSendLen != (int)strSendBuf.size())
{
   closesocket(m_hSocket);
   m_hSocket = 0;
   return false;
}

//回复
return CheckResponse(250);
}

bool SmtpSendEmail::QuitServ()
{
string strSendBuf = "QUIT/r/n";
int nSendLen = send(m_hSocket, strSendBuf.c_str(), (int)strSendBuf.size(), 0);
if (nSendLen != (int)strSendBuf.size())
{
   closesocket(m_hSocket);
   m_hSocket = 0;
   return false;
}

//回复
return CheckResponse(221);
}

测试代码:

m_smtp.SetHost("smtp.126.com");
m_smtp.SetPost(25);
m_smtp.SetAccount("yefeng654321");
m_smtp.SetPassword("密码");
m_smtp.SetMailFrom("yefeng654321@126.com");
m_smtp.SetSendTo("yefeng654321@126.com");
m_smtp.SetSubject("测试");
m_smtp.SetDateTime("2008-12-29");
m_smtp.AddDataFromBuffer("123456789", 9);
m_smtp.AddAttachedFile("c://","1.txt");
m_smtp.StarMailThread();

发上源程序在VC2005下调试通过,希望对朋友们有用!