What is the best way to block email with encoded subject header with
=?utf-8?B?WzM0MDkzODld5ZyG5Lit5Zu95bel5Lia5qKm77ya44CK5Lqn5ZOB5aSn5YWo5ZKM5bqU55So5qGI5L6L5omL5YaM44CLKDIwMTPlubQp5YWN6LS55LiL6L29KDMy6aG1LOmrmOa4hSw3TSxQREbmoLzlvI8pWzYwZzJqMDk5aHVzZnMwYWhja2FjZm00c3dyazlwd3o5M2dmbm1nbHo0Ym50ZV0=?=
