diff --git a/src/connection/enterprise.js b/src/connection/enterprise.js
index 68db4819e..1fa2ff22d 100644
--- a/src/connection/enterprise.js
+++ b/src/connection/enterprise.js
@@ -133,7 +133,9 @@ export function isHRDDomain(m, email) {
 
 export function toggleHRD(m, email) {
   if (email) {
-    m = setUsername(m, emailLocalPart(email), "username", false);
+    const username = l.defaultADUsernameFromEmailPrefix(m) ? emailLocalPart(email) : email;
+
+    m = setUsername(m, username, "username", false);
     m = tset(m, "hrdEmail", email);
   } else {
     m = tremove(m, "hrdEmail");
diff --git a/src/connection/enterprise/actions.js b/src/connection/enterprise/actions.js
index c7668055d..a4309e1e1 100644
--- a/src/connection/enterprise/actions.js
+++ b/src/connection/enterprise/actions.js
@@ -6,7 +6,9 @@ import {
   toggleHRD
 } from '../enterprise';
 import { getFieldValue, hideInvalidFields } from '../../field/index';
+import { emailLocalPart } from '../../field/email';
 import { logIn as coreLogIn } from '../../core/actions';
+import * as l from '../../core/index';
 
 // TODO: enterprise connections should not depend on database
 // connections. However, we now allow a username input to contain also
@@ -49,8 +51,10 @@ function logInActiveFlow(id) {
     ? "username"
     : "email";
 
-  const username = getFieldValue(m, usernameField);
-  const connection = enterpriseActiveFlowConnection(m); 
+  const originalUsername = getFieldValue(m, usernameField);
+  const connection = enterpriseActiveFlowConnection(m);
+
+  const username = l.defaultADUsernameFromEmailPrefix(m) ? emailLocalPart(originalUsername) : originalUsername;
 
   coreLogIn(id, ["password", usernameField], {
     connection: connection ? connection.get("name") : null,
diff --git a/src/connection/enterprise/hrd_screen.jsx b/src/connection/enterprise/hrd_screen.jsx
index 64e622ddf..96a16e524 100644
--- a/src/connection/enterprise/hrd_screen.jsx
+++ b/src/connection/enterprise/hrd_screen.jsx
@@ -10,9 +10,9 @@ const Component = ({i18n, model}) => {
   const domain = enterpriseDomain(model);
 
   var headerText;
-  
+
   if (domain != null) {
-    headerText = i18n.html("enterpriseActiveLoginInstructions", domain);     
+    headerText = i18n.html("enterpriseActiveLoginInstructions", domain);
   } else {
     headerText = i18n.html("enterpriseLoginIntructions");
   }
diff --git a/src/core/index.js b/src/core/index.js
index b27da5bd3..079779e27 100644
--- a/src/core/index.js
+++ b/src/core/index.js
@@ -36,7 +36,8 @@ export function setup(id, clientID, domain, options, hookRunner, emitEventFn) {
     useTenantInfo: options.__useTenantInfo || false,
     hashCleanup: options.hashCleanup === false ? false : true,
     allowedConnections: Immutable.fromJS(options.allowedConnections || []),
-    ui: extractUIOptions(id, options)
+    ui: extractUIOptions(id, options),
+    defaultADUsernameFromEmailPrefix: options.defaultADUsernameFromEmailPrefix === false ? false : true
   }));
 
   m = i18n.initI18n(m);
@@ -323,6 +324,10 @@ export function loggedIn(m) {
   return tget(m, "loggedIn", false);
 }
 
+export function defaultADUsernameFromEmailPrefix(m) {
+  return get(m, "defaultADUsernameFromEmailPrefix", true);
+}
+
 export function warn(x, str) {
   const shouldOutput = Map.isMap(x)
     ? !ui.disableWarnings(x)