SMTP cliat with SSL connection

I have next sample code of using SMPT client, when I am tring to send mail via mail which uses SSl I am getting next error:

550 SMTP is available only with SSL or TLS connection enabled.

How I can exend this sample for using SSL, for example to send e-mails via gmail, etc... I am interesting of using sockets and no exrnal lybrary:

int main()
{
  if (FAILED (WSAStartup (MAKEWORD( 1,1 ), &ws))) 
  { 
    printf("Error in WSAStartup(...)\n");
    return 1; }

  // creating socket
  s = socket (AF_INET, SOCK_STREAM, 0);
  if (s == INVALID_SOCKET) 
  { 
    printf("Error in socket(...)\n");
    return 1;  }

  //get server address
  d_addr = gethostbyname ("smtp.mail.ru");
  if (d_addr==NULL)
  {
    printf("Error in gethostbyname(...)\n");
    return 1;  };

  // fill address parameters
  addr.sin_family = AF_INET; 
  addr.sin_addr.s_addr = *((unsigned long *) d_addr->h_addr);
  addr.sin_port = htons (25);

  // connecting...
  if (SOCKET_ERROR == (connect (s, (sockaddr *) &addr,
                       sizeof (addr)))) 
  { 
    printf("Error in connect(...)\n");
    return 1; }

  // waiting from answer from server
  recv(s,text,sizeof(text),0);
  printf("recv - %s", text);

  // sy hello to server
  strcpy(text,"HELO smtp.mail.ru\r\n");
  send(s,text,strlen(text),0);
  printf("send - %s", text);

  // waiting approve from server
  recv(s,text,sizeof(text),0);
  printf("recv - %s", text);

  // set sender
  strcpy(text,"MAIL FROM: sender@mail.ru\r\n");
  send(s,text,strlen(text),0);
  printf("send - %s", text);

  // waiting for approve
  recv(s,text,sizeof(text),0);
  printf("recv - %s", text);

  // set receiver
  strcpy(text,"RCPT TO: receiver@mtu-net.ru\r\n");
  send(s,text,strlen(text),0);
  printf("send - %s", text);

  // waiting for approve
  recv(s,text,sizeof(text),0);
  printf("recv - %s", text);

  // ready to start sending letter
  strcpy(text,"DATA\r\n");
  send(s,text,strlen(text),0);
  printf("send - %s", text);

  // waiting for approve
  recv(s,text,sizeof(text),0);
  printf("recv - %s", text);

  // from whom letter
  strcpy(text,"FROM: sender@mail.ru\r\n");
  send(s,text,strlen(text),0);
  printf("send - %s", text);

  // receiver
  strcpy(text,"TO: receiver@mtu-net.ru\r\n");
  send(s,text,strlen(text),0);
  printf("send - %s", text);

  // letter subject
  strcpy(text,"SUBJECT: test\r\n");
  send(s,text,strlen(text),0);
  printf("send - %s", text);

  // letter text
  strcpy(text,"Hi!\nIt is a message for you\n");
  send(s,text,strlen(text),0);
  printf("send - %s", text);

  // telling that we finish
  strcpy(text,"\r\n.\r\n");
  send(s,text,strlen(text),0);
  printf("send - %s", text);
  recv(s,text,sizeof(text),0);
  printf("recv - %s", text);

  // quit
  strcpy(text,"QUIT");
  send(s,text,strlen(text),0);
  printf("send - %s", text);

  // close socket
  closesocket(s);

  return 0;
}