diff --git a/webui/controller/user/add.php b/webui/controller/user/add.php
index 5da8c612..7bc8d63e 100644
--- a/webui/controller/user/add.php
+++ b/webui/controller/user/add.php
@@ -107,7 +107,7 @@ private function validate() {
       else {
          $emails = explode("\n", $this->request->post['email']);
          foreach ($emails as $email) {
-            $email = rtrim($email);
+            $email = strtolower(rtrim($email));
             if($email == '') { continue; }
 
             $ret = checkemail($email, $this->domains);
diff --git a/webui/controller/user/edit.php b/webui/controller/user/edit.php
index 1544a913..e66b5aa7 100644
--- a/webui/controller/user/edit.php
+++ b/webui/controller/user/edit.php
@@ -113,7 +113,7 @@ class ControllerUserEdit extends Controller {
       } else {
          $emails = explode("\n", $this->request->post['email']);
          foreach ($emails as $email) {
-            $email = rtrim($email);
+            $email = strtolower(rtrim($email));
 
             if($email == '') { continue; }