CURLOPT_MAIL_AUTH - SMTP authentication address
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_MAIL_AUTH, char *auth);
Pass a pointer to a null-terminated string as parameter. This will be used to
specify the authentication address (identity) of a submitted message that is
being relayed to another server.
This optional parameter allows co-operating agents in a trusted
environment to communicate the authentication of individual messages and
should only be used by the application program, using libcurl, if the
application is itself a mail server acting in such an environment. If the
application is operating as such and the AUTH address is not known or is
invalid, then an empty string should be used for this parameter.
Unlike CURLOPT_MAIL_FROM(3) and
CURLOPT_MAIL_RCPT(3), the address should not be specified within a
pair of angled brackets (<>). However, if an empty string is used then
a pair of brackets will be sent by libcurl as required by RFC2554.
The application does not have to keep the string around after
setting this option.
CURL *curl = curl_easy_init();
curl_easy_setopt(curl, CURLOPT_URL, "smtp://example.com/");
curl_easy_setopt(curl, CURLOPT_MAIL_AUTH, "<secret@cave>");
ret = curl_easy_perform(curl);
Returns CURLE_OK if the option is supported, CURLE_UNKNOWN_OPTION if not, or
CURLE_OUT_OF_MEMORY if there was insufficient heap space.