Ticket #17491: 17491.diff

wp-includes/formatting.php

@@ -1512 +1512 @@
 
         // LOCAL PART
         // Test for invalid characters
-        if ( !preg_match( '/^[a-zA-Z0-9!#$%&\'*+\/=?^_`{|}~\.-]+$/', $local ) ) {
+        if ( ! preg_match( '/^[a-z0-9!#$%&\'*+\/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&\'*+\/=?^_`{|}~-]+)*$/i', $local ) ) {
                 return apply_filters( 'is_email', false, $email, 'local_invalid_chars' );
         }