diff --git a/src/Oro/Bundle/EmailBundle/Builder/EmailEntityBatchProcessor.php b/src/Oro/Bundle/EmailBundle/Builder/EmailEntityBatchProcessor.php
index 433de5bdcab..c07fdab000b 100644
--- a/src/Oro/Bundle/EmailBundle/Builder/EmailEntityBatchProcessor.php
+++ b/src/Oro/Bundle/EmailBundle/Builder/EmailEntityBatchProcessor.php
@@ -90,7 +90,7 @@ public function addEmailUser(EmailUser $obj)
      */
     public function addAddress(EmailAddress $obj)
     {
-        $key = strtolower($obj->getEmail());
+        $key = transliterator_transliterate('Any-Latin;Latin-ASCII;Lower;', $obj->getEmail());
         if (isset($this->addresses[$key])) {
             throw new \LogicException(sprintf('The email address "%s" already exists in the batch.', $obj->getEmail()));
         }