Number of processes and connections of builtin zone MTA is now configurable via Mailtrains config.

server/config/default.yaml

@@ -217,6 +217,8 @@ builtinZoneMTA:
   redis: redis://localhost:6379/2
   log:
     level: warn
+  processes: 2
+  connections: 5
 
 seleniumWebDriver:
   browser: phantomjs

server/lib/builtin-zone-mta.js

@@ -108,8 +108,8 @@ async function createConfig() {
             default: {
                 preferIPv6: false,
                 ignoreIPv6: true,
-                processes: 1,
+                processes: config.builtinZoneMTA.processes,
-                connections: 5,
+                connections: config.builtinZoneMTA.connections,
                 pool: 'default'
             }
         }