+/* There may be very many supplementary groups for the user. See notes
+in "man 2 getgroups". */
+#define _DARWIN_UNLIMITED_GETGROUPS
+#define EXIM_GROUPLIST_SIZE 64
+
+/* TCP Fast Open: Darwin uses a connectx() call
+rather than a modified sendto() */
+#define EXIM_TFO_CONNECTX
+
+/* MacOS, at least on the buildfarm animal, does not seem to push out
+the SMTP response to QUIT with our usual handling which is trying to get
+the client to FIN first so that the server does not get the TIME_WAIT */
+#define SERVERSIDE_CLOSE_NOWAIT
+