--- /dev/null
+# callout with no transport
+need_ipv4
+#
+server PORT_S
+220 Welcome
+HELO
+250 Hi
+MAIL FROM
+250 OK
+RCPT TO
+550 unrouteable address
+QUIT
+221 Bye
+****
+exim -bs
+mail from:<unknown@x.x.x.x>
+rcpt to:<unknown@u.u.u.u>
+quit
+****