CURLOPT\_UPLOAD\_FLAGS(3) Library Functions Manual CURLOPT\_UPLOAD\_FLAGS(3)

# [NAME](#NAME)

CURLOPT\_UPLOAD\_FLAGS - upload flags for IMAP

# [SYNOPSIS](#SYNOPSIS)

```
#include <curl/curl.h>
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_UPLOAD_FLAGS, long bitmask);
```

# [DESCRIPTION](#DESCRIPTION)

Pass a long as parameter, which is set to a bitmask, to tell libcurl which flags to send the server relating to uploaded files. The currently supported flags are:

[CURLULFLAG\_ANSWERED](#CURLULFLAG_ANSWERED)

Sets the **Answered** flag for IMAP uploads. Indicates that the message has been replied to.

[CURLULFLAG\_DELETED](#CURLULFLAG_DELETED)

Sets the **Deleted** flag for IMAP uploads. Marks the message for deletion rather than immediately removing it.

[CURLULFLAG\_DRAFT](#CURLULFLAG_DRAFT)

Sets the **Draft** flag for IMAP uploads. Marks the message as an uncompleted composition.

[CURLULFLAG\_FLAGGED](#CURLULFLAG_FLAGGED)

Sets the **Flagged** flag for IMAP uploads. Marks the message for special attention.

[CURLULFLAG\_SEEN](#CURLULFLAG_SEEN)

Sets the **Seen** flag for IMAP uploads. Marks the message as read.

# [DEFAULT](#DEFAULT)

A bitmask with only the **CURLULFLAG\_SEEN** flag set.

# [PROTOCOLS](#PROTOCOLS)

This functionality affects imap and imaps

# [EXAMPLE](#EXAMPLE)

```
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](#AVAILABILITY)

Added in curl 8.13.0

# [RETURN VALUE](#RETURN_VALUE)

[*curl\_easy\_setopt(3)*](/man/os/curl/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)*](/man/os/curl/libcurl-errors.3).

# [SEE ALSO](#SEE_ALSO)

[**CURLOPT\_UPLOAD**(3)](/man/os/curl/CURLOPT_UPLOAD.3)

2026-10-22 libcurl

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Document: CURLOPT_UPLOAD_FLAGS(3) from curl 8.23.0-r2 (Chainguard OS)
Source: https://github.com/curl/curl.git