Added extension hook for modifying submission export columns

code/UserForm.php

@@ -325,6 +325,8 @@ SQL;
         // attach every column to the print view form
         $columns['Created'] = 'Created';
         $columns['SubmittedBy.Email'] = 'Submitter';
+        $this->extend('updateSubmissionsGridFieldExportColumns', $columns);
+
         $filter->setColumns($columns);
 
         // print configuration