improve log message for queue* hooks

Changes.md

@@ -14,6 +14,7 @@
 - avg: repackaged as NPM module #3347
 - bounce: repackaged plugin as NPM module #3341
 - connection: check remote is connected before queue #3338
+  - improve log message for queue* hooks, fixes #2998
   - support IPv6 when setting remote.is_private #3295
   - in setTLS, replace forEach with for...of
   - NOTE: remove a handful of 3.0 sunset property names #3315

connection.js

@@ -170,7 +170,7 @@
             self.fail();
         });
 
         self.client.on('close', has_error => {
             if (self.state >= states.DISCONNECTING) return;
             self.remote.closed = true;
             self.loginfo('client dropped connection', log_data);
@@ -202,7 +202,7 @@
 
         const ha_list = net.isIPv6(self.remote.ip) ? haproxy_hosts_ipv6 : haproxy_hosts_ipv4;
 
         if (ha_list.some((element, index, array) => {
             return ipaddr.parse(self.remote.ip).match(element[0], element[1]);
         })) {
             self.proxy.allowed = true;
@@ -686,7 +686,7 @@
     }
     /////////////////////////////////////////////////////////////////////////////
     // SMTP Responses
     connect_init_respond (retval, msg) {
         // retval and message are ignored
         this.logdebug('running connect_init_respond');
         plugins.run_hooks('lookup_rdns', this);
@@ -902,7 +902,7 @@
             }
         }
     }
     capabilities_respond (retval, msg) {
         this.respond(250, this.capabilities);
     }
     quit_respond (retval, msg) {
@@ -1701,7 +1701,12 @@
         });
     }
     queue_msg (retval, msg) {
-        if (msg) return msg;
+        if (msg) {
+            if (typeof msg === 'object' && msg.constructor.name === 'DSN') {
+                return msg.reply
+            }
+            return msg;
+        }
 
         switch (retval) {
             case constants.ok:
@@ -1737,7 +1742,7 @@
     }
     queue_outbound_respond (retval, msg) {
         if (this.remote.closed) return;
-        if (!msg) msg = this.queue_msg(retval, msg) || 'Message Queued';
+        msg = this.queue_msg(retval, msg) || 'Message Queued';
         this.store_queue_result(retval, msg);
         msg = `${msg} (${this.transaction.uuid})`;
         if (retval !== constants.ok) {
@@ -1813,7 +1818,7 @@
         }
     }
     queue_respond (retval, msg) {
-        if (!msg) msg = this.queue_msg(retval, msg);
+        msg = this.queue_msg(retval, msg);
         this.store_queue_result(retval, msg);
         msg = `${msg} (${this.transaction.uuid})`;