CURLcode curl_easy_setopt(CURL *handle, CURLOPT_MAIL_FROM, char *from);
DESCRIPTIONPass a pointer to a zero terminated string as parameter. This should be used to specify the sender's email address when sending SMTP mail with libcurl.
An originator email address should be specified with angled brackets (<>) around it, which if not specified will be added automatically.
If this parameter is not specified then an empty address will be sent to the mail server which may cause the email to be rejected.