smtp_mail: Added support to MAIL FROM for the optional AUTH parameter

Added a new CURLOPT_MAIL_AUTH option that allows the calling program to
set the optional AUTH parameter in the MAIL FROM command.

When this option is specified and an authentication mechanism is used
to communicate with the mail server then the AUTH parameter will be
included in the MAIL FROM command. This is particularly useful when the
calling program is acting as a relay in a trusted environment and
performing server to server communication, as it allows the relaying
server to specify the address of the mailbox that was used to
authenticate and send the original email.

1 files changed, 5 insertions, 0 deletions

diff --git a/lib/url.c b/lib/url.c
index 277078ebf..c4e84550f 100644
--- a/lib/url.c
+++ b/lib/url.c
@@ -2402,6 +2402,11 @@ CURLcode Curl_setopt(struct SessionHandle *data, CURLoption option,
                        va_arg(param, char *));
     break;
 
+  case CURLOPT_MAIL_AUTH:
+    result = setstropt(&data->set.str[STRING_MAIL_AUTH],
+                       va_arg(param, char *));
+    break;
+
   case CURLOPT_MAIL_RCPT:
     /* get a list of mail recipients */
     data->set.mail_rcpt = va_arg(param, struct curl_slist *);