diff --git a/README.md b/README.md
index 31d4325..c383ec7 100644
--- a/README.md
+++ b/README.md
@@ -72,10 +72,11 @@ For other distributions please follow your specific steps.
 
 ```json
 {
-  "urlMainWindow": "https://customurl.example/",
-  "urlsInternal": ["customurl.example"],
-  "urlsExternal": ["externalurls.example"],
-  "showWindowFrame": true
+ "urlMainWindow":"https://customurl.example/",
+ "deeplinkUrls":["customurl.example"],
+ "outlookUrls":["outlookurls.example"],
+ "externalUrls": ["externalurls.example"],
+ "showWindowFrame":true
 }
 ```
 
@@ -88,11 +89,12 @@ Outlook.com account:
 ```json
 {
   "urlMainWindow": "https://outlook.live.com/mail",
-  "urlsInternal": ["outlook.com", "live.com"],
-  "urlsExternal": ["outlook.com", "live.com"]
+  "deeplinkUrls": ["outlook.com", "live.com"],
+  "outlookUrls": ["outlook.com", "live.com"]
 }
 ```
 
+
 ### Architecture components
 
 The main software architecture components and their versions are this:
diff --git a/src/controller/mail-window-controller.js b/src/controller/mail-window-controller.js
index 67f9360..7375cf2 100644
--- a/src/controller/mail-window-controller.js
+++ b/src/controller/mail-window-controller.js
@@ -11,8 +11,10 @@ const settings = require("electron-settings");
 const getClientFile = require("./client-injector");
 const path = require("path");
 
+
 let outlookUrl;
 let deeplinkUrls;
+let externalUrls;
 let outlookUrls;
 let showWindowFrame;
 let $this;
@@ -47,10 +49,14 @@ class MailWindowController {
       "outlook.office365.com",
       "outlook.office.com",
     ];
+    externalUrls = settings.getSync('externalUrls') || [
+      'outlook.office.com/mail/safelink.html'
+    ]
     console.log("Loaded settings", {
       outlookUrl: outlookUrl,
       deeplinkUrls: deeplinkUrls,
       outlookUrls: outlookUrls,
+      externalUrls: externalUrls,
     });
   }
   init() {
@@ -195,20 +201,27 @@ class MailWindowController {
 
   openInBrowser(e, url, frameName, disposition, options) {
     console.log("Open in browser: " + url); //frameName,disposition,options)
-    if (new RegExp(deeplinkUrls.join("|")).test(url)) {
-      // Default action - if the user wants to open mail in a new window - let them.
-      //e.preventDefault()
-      console.log("Is deeplink");
-      options.webPreferences.affinity = "main-window";
-    } else if (new RegExp(outlookUrls.join("|")).test(url)) {
-      // Open calendar, contacts and tasks in the same window
-      e.preventDefault();
-      this.loadURL(url);
-    } else {
-      // Send everything else to the browser
-      e.preventDefault();
-      shell.openExternal(url);
+
+    if (!new RegExp(externalUrls.join("|")).test(url)) {
+      if (new RegExp(deeplinkUrls.join("|")).test(url)) {
+        // Default action - if the user wants to open mail in a new window - let them.
+        //e.preventDefault()
+        console.log("Is deeplink, open in main window");
+        options.webPreferences.affinity = "main-window";
+        return;
+      }
+      if (new RegExp(outlookUrls.join("|")).test(url)) {
+        // Open calendar, contacts and tasks in the same window
+        console.log("Is outlook URL, open in application");
+        e.preventDefault();
+        this.loadURL(url);
+        return;
+      }
     }
+    // Send everything else to the browser
+    console.log("Is external URL, open in browser");
+    e.preventDefault();
+    shell.openExternal(url);
   }
 
   show() {
@@ -253,7 +266,6 @@ class MailWindowController {
         );
       }
       //console.log(params)
-
       for (const flag in params.editFlags) {
         let actionLabel = flag.substring(3); //remove "can"
         if (flag == "canSelectAll") {