-# Client requests notification of deferral. First time of trying, the
-# queue-time probably has not hit the 1st retry time yet, so no DSN will
-# be sent and the message remains queued.
+# MSA send msg to MDA
+exim -q
+****
+# deliver msg at MDA
+exim -q
+****
+# deliver notification from MDA
+exim -q
+****
+#
+# Client requests notification of deferral. First time of trying, we get
+# a defer but queue-time probably has not hit the 1st retry time yet, so no DSN
+# will be sent and the message remains queued. Later, after a sleep, we will
+# try again.
+exim -z defer/delay
+****