Admin: User import: Set e-mail to empty string if not provided. Don't check if e-mail is valid if it is not provided and not required - refs #3712

main/admin/user_import.php

@@ -131,7 +131,7 @@ function validate_data($users, $checkUniqueEmail = false)
         if (api_get_setting('registration', 'email') === 'false' && empty($user['Email'])) {
             $user['Email'] = '';
         }        
-        if (isset($user['Email'])) {                        
+        if (!empty($user['Email'])) {                        
             $result = api_valid_email($user['Email']);
             if ($result === false) {
                 $user['message'] .= Display::return_message(get_lang('PleaseEnterValidEmail'), 'warning');
@@ -140,7 +140,7 @@ function validate_data($users, $checkUniqueEmail = false)
         }
 
         if ($checkUniqueEmail) {
-            if (isset($user['Email'])) {
+            if (!empty($user['Email'])) {
                 $userFromEmail = api_get_user_info_from_email($user['Email']);
                 if (!empty($userFromEmail)) {
                     $user['message'] .= Display::return_message(get_lang('EmailUsedTwice'), 'warning');