.\" generated by cd2nroff 0.1 from CURLOPT_MAIL_AUTH.md
.TH CURLOPT_MAIL_AUTH 3 "2024-11-18" libcurl
.SH NAME
CURLOPT_MAIL_AUTH \- SMTP authentication address
.SH SYNOPSIS
.nf
#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_MAIL_AUTH, char *auth);
.fi
.SH DESCRIPTION
Pass a pointer to a null\-terminated string as parameter. This is 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 \fICURLOPT_MAIL_FROM(3)\fP and \fICURLOPT_MAIL_RCPT(3)\fP, the address should not
be specified within a pair of angled brackets (<>). However, if an empty
string is used then a pair of brackets are sent by libcurl as required by RFC
2554.

The application does not have to keep the string around after setting this
option.
.SH DEFAULT
NULL
.SH PROTOCOLS
This functionality affects smtp only
.SH EXAMPLE
.nf
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_MAIL_AUTH, "<secret@cave>");
    res = curl_easy_perform(curl);
    curl_easy_cleanup(curl);
  }
}
.fi
.SH AVAILABILITY
Added in curl 7.25.0
.SH RETURN VALUE
Returns CURLE_OK if the option is supported, CURLE_UNKNOWN_OPTION if not, or
CURLE_OUT_OF_MEMORY if there was insufficient heap space.
.SH SEE ALSO
.BR CURLOPT_MAIL_FROM (3),
.BR CURLOPT_MAIL_RCPT (3)