C++实现 电子邮件客户端程序（简易版）

#include <iostream>
#include <string>
#include <WinSock2.h> //适用平台 Windows
using namespace std;
#pragma comment(lib, "ws2_32.lib") /*链接ws2_32.lib动态链接库*/

int main()
{
     char buff[500]; //recv函数返回的结果
     string message;
     string info;
     string subject;

     WSADATA wsaData;
     WORD wVersionRequested = MAKEWORD(2, 1);
     //WSAStarup，即WSA(Windows SocKNDs Asynchronous，Windows套接字异步)的启动命令
     int err = WSAStartup(wVersionRequested, &wsaData);
    // cout << "WSAStartup:" << err << endl;
     SOCKET sockClient; //客户端的套接字
     sockClient = socket(AF_INET, SOCK_STREAM, 0); //建立socket对象

     HOSTENT* pHostent;//hostent是host entry的缩写，该结构记录主机的信息，包括主机名、别名、地址类型、地址长度和地址列表

     pHostent = gethostbyname("smtp.qq.com"); //得到有关于域名的信息,链接到qq邮箱服务器

     SOCKADDR_IN addrServer; //服务端地址
     addrServer.sin_addr.S_un.S_addr = *((DWORD *)pHostent->h_addr_list[0]); //得到smtp服务器的网络字节序的ip地址
     addrServer.sin_family = AF_INET;
     addrServer.sin_port = htons(25); //连接端口25
     //int connect (SOCKET s , const struct sockaddr FAR *name , int namelen ); //函数原型
     err = connect(sockClient, (SOCKADDR*)&addrServer, sizeof(SOCKADDR)); //向服务器发送请求
     //cout << "connect:" << err << endl;
     buff[recv(sockClient, buff, 500, 0)] = ‘\0‘;
    // cout << "connect:" << buff << endl;
     /*
     登录邮件服务器
     */
     message = "ehlo qq.com\r\n";
     send(sockClient, message.c_str(), message.length(), 0); //发送ehlo命令
     buff[recv(sockClient, buff, 500, 0)] = ‘\0‘;   //接收返回值
    // cout << "helo:" << buff << endl;     //输出返回值

     message = "auth login \r\n";
     send(sockClient, message.c_str(), message.length(), 0);
     buff[recv(sockClient, buff, 500, 0)] = ‘\0‘;
     //cout << "auth login:" << buff << endl;
     /*
     发送base64加密的用户名、密码
     */

     message = "XXXXXXXX\r\n"; //base64 编码的用户名
     send(sockClient, message.c_str(), message.length(), 0);
     buff[recv(sockClient, buff, 500, 0)] = ‘\0‘;
     //cout << "usrname:" << buff << endl;

     message = "XXXXXXXXXXXX\r\n";//base64 编码的密码
     send(sockClient, message.c_str(), message.length(), 0);
     buff[recv(sockClient, buff, 500, 0)] = ‘\0‘;
    // cout << "password:" << buff << endl;
     /*
     使用 MAIL 命令指定发送者
     使用 RCPT 命令指定接收者，可以重复使用RCPT指定多个接收者
     */

     string mail;
     cout << "输入收件人邮箱：";
     cin >> mail;
     message = "MAIL FROM:<XXX@qq.com> \r\nRCPT TO:<";
    // message = "MAIL FROM:<XXX@qq.com> \r\nRCPT TO:<XXX@163.com> \r\n";

     message.append(mail);
     message.append("> \r\n");
     //cout << "message=" << message;

     send(sockClient, message.c_str(), message.length(), 0);

     buff[recv(sockClient, buff, 500, 0)] = ‘\0‘;
    // cout << "mail from: " << buff << endl;
     buff[recv(sockClient, buff, 500, 0)] = ‘\0‘;
    // cout << "rcpt to: " << buff << endl;
     /*
     使用 DATA 命令告诉服务器要发送邮件内容
     */
     message = "DATA\r\n";
     send(sockClient, message.c_str(), message.length(), 0);
     buff[recv(sockClient, buff, 500, 0)] = ‘\0‘;
     //cout << "data: " << buff << endl;

    message = "From: XXX@qq.com\r\n\
    To: XXX@163.com\r\n\
    subject:";

    cout<<"主题：";
    cin>>subject;
    message.append(subject);
    message.append("\r\n\r\n");
    cout<<"内容：";
    cin>>info;
    message.append(info);
    message.append("\r\n.\r\n");

   // cout<<"message="<<message;

     /*message = "From: XXX@qq.com\r\n\
    To: XXX@163.com\r\n\
    subject: test\r\n\r\n\
    Just a test!\r\n\
    your friend\r\n\
    Ctt\r\n.\r\n"; //注意subject关键字与正文之间要有一个空行*/

     send(sockClient, message.c_str(), message.length(), 0);
     message = "QUIT\r\n";
     send(sockClient, message.c_str(), message.length(), 0);
    buff[recv(sockClient, buff, 500, 0)] = ‘\0‘;
     //cout << "QUIT:" << buff << endl;

     cout << "发送成功！"<<endl;
     system("pause");
}