1 files changed, 1 insertions, 0 deletions
diff --git a/lib/smtp.h b/lib/smtp.h
index e2a19c639..db1b1e672 100644
--- a/lib/smtp.h
+++ b/lib/smtp.h
@@ -86,6 +86,7 @@ struct smtp_conn {
   bool size_supported;     /* If server supports SIZE extension according to
                               RFC 1870 */
   bool auth_supported;     /* AUTH capability supported by server */
+  bool mutual_auth;        /* Mutual authentication enabled (GSSAPI only) */
 };
 
 extern const struct Curl_handler Curl_handler_smtp;