CURLOPT_CRLF − enable/disable CRLF conversion
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_CRLF, long conv);
Pass a long. If the value is set to 1 (one), libcurl converts Unix newlines to CRLF newlines on transfers. Disable this option again by setting the value to 0 (zero).
This is a legacy option of questionable use.
CURL *curl =
curl_easy_setopt(curl, CURLOPT_URL, "ftp://example.com/");
curl_easy_setopt(curl, CURLOPT_CRLF, 1L);
ret = curl_easy_perform(curl);
SMTP since 7.40.0, other protocols since they were introduced