diff --git a/src/mailboxdb.js b/src/mailboxdb.js
index f236eb916..37f15e46f 100644
--- a/src/mailboxdb.js
+++ b/src/mailboxdb.js
@@ -39,7 +39,7 @@ function add(name, ownerId, ownerType, callback) {
     assert.strictEqual(typeof callback, 'function');
 
     database.query('INSERT INTO mailboxes (name, ownerId, ownerType) VALUES (?, ?, ?)', [ name, ownerId, ownerType ], function (error) {
-        if (error && error.code === 'ER_DUP_ENTRY') return callback(new DatabaseError(DatabaseError.ALREADY_EXISTS));
+        if (error && error.code === 'ER_DUP_ENTRY') return callback(new DatabaseError(DatabaseError.ALREADY_EXISTS, 'mailbox already exists'));
         if (error) return callback(new DatabaseError(DatabaseError.INTERNAL_ERROR, error));
 
         callback(null);
diff --git a/webadmin/src/views/users.js b/webadmin/src/views/users.js
index 3434e5f1e..2fc9ee2ca 100644
--- a/webadmin/src/views/users.js
+++ b/webadmin/src/views/users.js
@@ -107,16 +107,15 @@ angular.module('Application').controller('UsersController', ['$scope', '$locatio
                         $scope.useradd.error.email = 'Email already taken';
                         $scope.useradd_form.email.$setPristine();
                         $('#inputUserAddEmail').focus();
-                        return;
-                    } else if (error.message.toLowerCase().indexOf('username') !== -1) {
+                    } else if (error.message.toLowerCase().indexOf('username') !== -1 || error.message.toLowerCase().indexOf('mailbox') !== -1) {
                         $scope.useradd.error.username = 'Username already taken';
                         $scope.useradd_form.username.$setPristine();
                         $('#inputUserAddUsername').focus();
                     } else {
                         // should not happen!!
                         console.error(error.message);
-                        return;
                     }
+                    return;
                 }
                 if (error && error.statusCode === 400) {
                     if (error.message.indexOf('email') !== -1) {