C语言 发送电子邮件

我用C 语言实现了连接126邮件服务器发送邮件,网上有很多例子,我下了,没有一个能运行起来的,这个是用netbean测试,没有问题了,下面是我的代码(要改三处地方:用户名\密码\发送邮件):
#include <stdio.h>
#include <winsock2.h>
#include <stdlib.h>
#include <string.h>

//#pragma comment(lib,"ws2_32.lib")

// Function prototype
void StreamClient(char *szServer, short nPort, char *szMessage);
// Helper macro for displaying errors
#define PRINTERROR(s) \
fprintf(stderr,"\n%: %d\n", s, WSAGetLastError())





int main(int argc, char **argv)
{
char hostname[255];

WORD wVersionRequested = MAKEWORD(2,0);
WSADATA wsaData;
int nRet;
short nPort;

nPort =25;
nRet = WSAStartup(wVersionRequested, &wsaData);

StreamClient("smtp.126.com", nPort, "AUTH LOGIN\r\n");


WSACleanup();
return 0;
}



void StreamClient(char *szServer, short nPort, char *szMessage)
{
printf("\nStream Client connecting to server: %s on port: %d",szServer, nPort);

//
// Find the server
//
LPHOSTENT lpHostEntry;

lpHostEntry = gethostbyname(szServer);
if (lpHostEntry == NULL)
{
PRINTERROR("gethostbyname()");
return;
}

//
// Create a TCP/IP stream socket
//
SOCKET theSocket;

theSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
if (theSocket == INVALID_SOCKET){
PRINTERROR("socket()");
return;
}

//
// Fill in the address structure
//
SOCKADDR_IN saServer;

saServer.sin_family = AF_INET;
saServer.sin_addr = *((LPIN_ADDR)*lpHostEntry->h_addr_list);
saServer.sin_port = htons(nPort);

//
// connect to the server
//
int nRet;

nRet = connect( theSocket, // Socket
(LPSOCKADDR)&saServer, // Server address
sizeof(struct sockaddr));// Length of server address structure
printf("\n%d1lL=====================================%d\n",nRet,SOCKET_ERROR);
if (nRet == SOCKET_ERROR)
{
PRINTERROR("socket()");
closesocket(theSocket);
return;
}


char szBuf[256];


// strcpy(szBuf, "From the Client");
char buf[350]="0";
char server[250];
gethostname(server,250);
strcpy(buf, "HELO ");

strcat(buf, server);
strcat(buf, " \r\n");
printf("%s:::%d",buf,strlen(buf));

//
// Wait for a reply
//
nRet = recv(theSocket,szBuf,sizeof(szBuf)+1,0); printf("\nData received OVER DATA: %s", szBuf);

nRet = send(theSocket, buf, strlen(buf), 0);
nRet = recv(theSocket, szBuf, sizeof(szBuf), 0); printf("\nData received2: %s", szBuf);

//发送准备登陆信息
nRet = send(theSocket, "AUTH LOGIN \r\n", sizeof("AUTH LOGIN \r\n"), 0);
nRet = recv(theSocket, szBuf, sizeof(szBuf), 0); printf("\nData received LOGIN: %s", szBuf);

//发送用户名和密码,这里的用户名和密码必须用base64进行转码,发送转码以后的字符串
nRet = send(theSocket,"用户名\r\n", strlen("用户名\r\n"),0);
nRet = recv(theSocket, szBuf, sizeof(szBuf),0);printf("\nData receivedUSERNAME: %s", szBuf);

//发送用户密码
nRet = send(theSocket,"密码\r\n", strlen("密码\r\n"), 0);
nRet = recv(theSocket, szBuf, sizeof(szBuf),0); printf("\nData receivedUSERPASSWORD: %s", szBuf);

//发送[发送邮件]的信箱(改成你的邮箱!)
send(theSocket,"MAIL FROM:<geniues@126.com>\r\n",sizeof("MAIL FROM:<geniues@126.com>\r\n"),0);
nRet = recv(theSocket, szBuf, sizeof(szBuf)+1, 0);printf("\nData received MAILFROM: %s", szBuf);

//发送[接收邮件]的邮箱
nRet= send(theSocket,"RCPT TO:<geniues@qq.com> \r\n",sizeof("RCPT TO:<geniues@qq.com> \r\n"),0);
nRet = recv(theSocket, szBuf, sizeof(szBuf)+1, 0); printf("\nData received TOMAIL: %s", szBuf);

char MailData[1024] =
"From: \"geniues@126.com\"\r\n"
"To: maxinliang002@126.com\r\n"
"Subject: IP Address\r\n\r\n"; //主题可以改成别的

//各诉邮件服务器，准备发送邮件内容
send(theSocket,"DATA\r\n", strlen("DATA\r\n"),0);
nRet = recv(theSocket, szBuf, sizeof(szBuf)+1, 0); printf("\nData receivedSEND DATA: %s", szBuf);
//发送邮件标题
send(theSocket,MailData, strlen(MailData),0);
//发送邮件内容
send(theSocket,"邮件内容来了!\r\n", strlen("邮件内容来了!\r\n"),0);
//发送邮件结束
send(theSocket,"\r\n.\r\n", strlen("\r\n.\r\n"),0);
//接收邮件服务器返回信息
nRet = recv(theSocket,szBuf,sizeof(szBuf)+1,0); printf("\nData received OVER DATA: %s", szBuf);


//
// Display the received data
//
//printf("\nData received3: %s", szBuf);


closesocket(theSocket);
return;
}