Exchange 2003 Reverse NDR attack - recipient filtering does not work.
Posted on 2010-08-26
We have suffered a reverse NDR attack and I have turned on recipient filtering in Exchange 2003 SP2, both at the Message Delivery settings and on the Virtual SMTP server. However, the attack continues because bad mail is still being received and NDRs are still being generated and sent out. Does anyone know why this might be and what I can do to stop the generation of NDRs?