CURLOPT_SASL_IR(3) Library Functions Manual CURLOPT_SASL_IR(3) NAME CURLOPT_SASL_IR - send initial response in first packet SYNOPSIS #include CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SASL_IR, long enable); DESCRIPTION Pass a long. If the value is 1, curl sends 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. DEFAULT 0 PROTOCOLS This functionality affects imap and smtp EXAMPLE int main(void) { CURL *curl = curl_easy_init(); if(curl) { CURLcode res; curl_easy_setopt(curl, CURLOPT_URL, "smtp://example.com/"); curl_easy_setopt(curl, CURLOPT_SASL_IR, 1L); res = curl_easy_perform(curl); curl_easy_cleanup(curl); } } AVAILABILITY Added in curl 7.31.0 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). SEE ALSO CURLOPT_MAIL_AUTH(3), CURLOPT_MAIL_FROM(3), CURLOPT_SASL_AUTHZID(3) libcurl 2025-02-08 CURLOPT_SASL_IR(3)