CURLOPT_UPLOAD_FLAGS(3)

okay bestie, welcome to CURLOPT_UPLOAD_FLAGS(3) — the manual page for upload flags for IMAP, and it's literally giving niche-but-iconic 💅

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🎀 NAME 🎀

CURLOPT_UPLOAD_FLAGS - upload flags for IMAP. That's the name, that's the vibe, and yes it's all about IMAP uploads 🎀

✨ SYNOPSIS ✨

#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_UPLOAD_FLAGS, long bitmask);

no cap, that's the whole signature 🫶

💖 DESCRIPTION 💖

okay so you pass a long as the parameter, and it gets set to a bitmask. This bitmask tells libcurl which flags to send the server relating to uploaded files. The currently supported flags are:

• CURLULFLAG_ANSWERED — sets the Answered flag for IMAP uploads. Indicates that the message has been replied to 💌
• CURLULFLAG_DELETED — sets the Deleted flag for IMAP uploads. Marks the message for deletion rather than immediately removing it. very "it's not gone yet, it's just on notice" energy 💀
• CURLULFLAG_DRAFT — sets the Draft flag for IMAP uploads. Marks the message as an uncompleted composition 🎀
• CURLULFLAG_FLAGGED — sets the Flagged flag for IMAP uploads. Marks the message for special attention. main character message behavior 👑
• CURLULFLAG_SEEN — sets the Seen flag for IMAP uploads. Marks the message as read 👀

🌸 DEFAULT 🌸

A bitmask with only the CURLULFLAG_SEEN flag set. so yes, seen is the default vibe, periodt ✨

🦋 PROTOCOLS 🦋

This functionality affects imap and imaps. literally those two 🦋

🍓 EXAMPLE 🍓

here's the example, and it's lowkey a whole meal — code is copied exactly, so don't @ me 🫶

static size_t read_cb(char *ptr, size_t size, size_t nmemb, void *userdata)
{
  FILE *src = userdata;
  /* copy as much data as possible into the 'ptr' buffer, but no more than
     'size' * 'nmemb' bytes */
  size_t retcode = fread(ptr, size, nmemb, src);

  return retcode;
}

int main(void)
{
  CURL *curl;
  FILE *src = fopen("local-file", "r");
  if(!src)
    return 1;

  curl = curl_easy_init();
  if(curl) {
    CURLcode result;
    curl_off_t fsize = 9876; /* set this to the size of the input file */

    /* we want to use our own read function */
    curl_easy_setopt(curl, CURLOPT_READFUNCTION, read_cb);

    /* enable uploading */
    curl_easy_setopt(curl, CURLOPT_UPLOAD, 1L);

    /* specify target */
    curl_easy_setopt(curl, CURLOPT_URL, "imap://example.com:993/mailbox");

    /* provide username */
    curl_easy_setopt(curl, CURLOPT_USERNAME, "user@example.com");

    /* provide password */
    curl_easy_setopt(curl, CURLOPT_PASSWORD, "password");

    /* specify that uploaded mail should be considered flagged */
    curl_easy_setopt(curl, CURLOPT_UPLOAD_FLAGS, CURLULFLAG_FLAGGED);

    /* now specify which pointer to pass to our callback */
    curl_easy_setopt(curl, CURLOPT_READDATA, src);

    /* Set the size of the file to upload */
    curl_easy_setopt(curl, CURLOPT_INFILESIZE_LARGE, (curl_off_t)fsize);

    /* perform the upload */
    result = curl_easy_perform(curl);
    curl_easy_cleanup(curl);
  }
  fclose(src);
}

🌈 AVAILABILITY 🌈

Added in curl 8.13.0 — noted, bestie ⭐

💜 RETURN VALUE 💜

curl_easy_setopt(3) returns a CURLcode indicating success or error.

CURLE_OK (0) means everything was OK, non-zero means an error occurred, see libcurl-errors(3). so if it's not 0, go peek at that page, iykyk 😭

👑 SEE ALSO 👑

• CURLOPT_UPLOAD(3) — the related page to check out, fr fr 🫶

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okay that's the whole page, bestie — brought to you by libcurl and dated 2026-10-25, and this manual page is CURLOPT_UPLOAD_FLAGS(3). mwah 💋✨