一.郵件下載：
1）相關函數
CURL *curl;
CURLcode res = CURLE_OK;
curl = curl_easy_init();
curl_easy_setopt(curl,CURLOPT_USERNAME,"USER"); //有的郵件服務器不能加域名比如，[email protected],qq.com不能要
curl_easy_setopt(curl,CURLOPT_PASSWORD,"123456");
curl_easy_setopt(curl,CURLOPT_URL,"pop3://test.com:110/1");
//110是默認端口，如果使用其他端口要跟着變，後面的1代表第幾份郵件
curl_easy_setopt(curl,CURLOPT_WRITEDATA,指針);
//指針，指示寫入數據需要存儲的地方，如文件或隊列
curl_easy_setopt(curl,CURLOPT_WRITEFUNCTION,,write_data);
//回調函數，上面的指針就是給其傳參數的作用，回調函數格式 static size_t write_data(coid *ptr,size_t size, size_t nmemb, void *stream);
stream就是上面的指針，ptr指向已經接受的數據，中間兩個相乘代表字節數
res = curl_easy_perform(curl);
if(res!=CURLE_OK)
fprintf(stderr,"%s",curl_easy_strerror(res));
curl_easy_cleanup(curl);
二.發送郵件
1）struct curl_slist *recipients=NULL;
curl = curl_easy_init();
curl_easy_setopt(curl,CURLOPT_URL,"smtp://to.com:25/from.com"); //默認端口25，可不寫，其他端口必須寫
curl_easy_setopt(curl,CURLOPT_MAIL_FROM,"[email protected]");
recipients = curl_slist_append(recipients,"[email protected]");
recipients = curl_slist_append(recipients,"[email protected]");
//抄送
curl_easy_setopt(curl,CURLOPT_MAIL_RCPT,recipients);
curl_easy_setopt(curl,CURLOPT_READDATA,指針);
//指針，指示寫入數據需要存儲的地方，如文件或隊列
curl_easy_setopt(curl,CURLOPT_READFUNCTION,read_data);
curl_easy_setopt(curl,CURLOPT_UPLOAD,1L);
// TRUE to prepare for an upload 設置非零值
res = curl_easy_perform(curl);
if(res!=CURLE_OK)
fprintf(stderr,"%s",curl_easy_strerror(res));
curl_easy_cleanup(curl);