用c++写一个发送邮件到QQ邮箱的示例

你好！下面是一个使用 C 语言发送邮件到 QQ 邮箱的示例：

首先，你需要安装和配置 libcurl 库，这是一个用于处理网络传输的库，支持多种协议，包括 SMTP。你可以在这里获取 libcurl 库：https://curl.haxx.se/libcurl/

然后，你可以使用下面的代码来发送邮件：

#include <stdio.h>
#include <curl/curl.h>

int main(void)
{
  CURL *curl;
  CURLcode res;

  curl = curl_easy_init();
  if(curl) {
    curl_easy_setopt(curl, CURLOPT_URL, "smtp://smtp.qq.com:587");
    curl_easy_setopt(curl, CURLOPT_USE_SSL, (long)CURLUSESSL_ALL);
    curl_easy_setopt(curl, CURLOPT_USERNAME, "your-email@qq.com");
    curl_easy_setopt(curl, CURLOPT_PASSWORD, "your-email-password");
    curl_easy_setopt(curl, CURLOPT_MAIL_FROM, "from@example.com");
    struct curl_slist *recipients = NULL;
    recipients = curl_slist_append(recipients, "to@example.com");
    curl_easy_setopt(curl, CURLOPT_MAIL_RCPT, recipients);
    curl_easy_setopt(curl, CURLOPT_READFUNCTION, NULL);
    curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L);
    curl_easy_setopt(curl, CURLOPT_POSTFIELDS, "To: to@example.com\r\n"
                                                "Subject: Test email using libcurl\r\n"
                                                "\r\n"
                                                "This is a test email message.\r\n");

    res = curl_easy_perform(curl);

    /* Check for errors */
    if(res != CURLE_OK)
      fprintf(stderr, "curl_easy_perform() failed: %s\n",
              curl_easy_strerror(res));

    /* Free the list of recipients */
    curl_slist_free_all(recipients);

    /* Always cleanup */
    curl_easy_cleanup(curl);
  }

  return (int)res;
}
``