relay: force STARTTLS when testing outbound relay

haraka only supports STARTTLS

src/mail.js

@@ -216,7 +216,8 @@ async function checkSmtpRelay(relay) {
         greetingTimeout: 5000,
         host: relay.host,
         port: relay.port,
-        secure: false // haraka relay only supports STARTTLS
+        secure: false, // true is for implicit TLS, false is for maybe STARTTLS
+        requireTLS: true // force STARTTLS . haraka only supports STARTTLS in outbound plugin
     };
 
     // only set auth if either username or password is provided, some relays auth based on IP (range)