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

#define USERNAME "username"
#define PASSWORD "password"
#define SERVER_URL "imap://mail.example.org/"

// This is the UID of the message that contains a line beginning with "+ "
#define BAD_MESSAGE_UID "2358"
#define FETCH_COMMAND "UID FETCH " BAD_MESSAGE_UID " (UID BODY.PEEK[1])"

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

    curl = curl_easy_init();
    if( curl ) {
        curl_easy_setopt(curl, CURLOPT_USERNAME, USERNAME);
        curl_easy_setopt(curl, CURLOPT_PASSWORD, PASSWORD);

        curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L);
        curl_easy_setopt(curl, CURLOPT_URL, SERVER_URL "INBOX");

        // Do the request
        curl_easy_setopt(curl, CURLOPT_CUSTOMREQUEST, FETCH_COMMAND);
        res = curl_easy_perform(curl);
        if( res != CURLE_OK ) {
            fprintf(stderr, "curl_easy_perform() failed: %s\n", curl_easy_strerror(res));
        }

        curl_easy_cleanup(curl);
    }

    return res;
}