CURLOPT_SASL_IR (3) - Linux Manuals
CURLOPT_SASL_IR: enable sending initial response in first packet
NAME
CURLOPT_SASL_IR - enable sending initial response in first packetSYNOPSIS
#include <curl/curl.h>CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SASL_IR, long enable);
DESCRIPTION
Pass a long. If the value is 1, curl will send the initial response to the server in the first authentication packet in order to reduce the number of ping pong requests. Only applicable to the following supporting SASL authentication mechanisms:* Login * Plain * GSSAPI * NTLM * OAuth 2.0
Note: Whilst IMAP supports this option there is no need to explicitly set it, as libcurl can determine the feature itself when the server supports the SASL-IR CAPABILITY.