Ability to not send welcome email (#10293)

no issue

- We need to be able to not send the welcome email if needed
- Intruduces a new possible config setting `sendWelcomeEmail` which is set to `true` by default

core/server/api/v0.1/authentication.js

@@ -531,6 +531,7 @@ authentication = {
 
             common.events.emit('setup.completed', setupUser);
 
+            if (config.get('sendWelcomeEmail')) {
                 return mail.utils.generateContent({data: data, template: 'welcome'})
                     .then((content) => {
                         const message = {
@@ -555,6 +556,9 @@ authentication = {
                     .return(setupUser);
             }
 
+            return setupUser;
+        }
+
         function formatResponse(setupUser) {
             return {users: [setupUser]};
         }

core/server/config/defaults.json

@@ -83,5 +83,6 @@
         "resize": true
     },
     "compress": true,
-    "preloadHeaders": false
+    "preloadHeaders": false,
+    "sendWelcomeEmail": true
 }