We have an issue with users not receiving Non-Delivery Reports when problems occur sending emails to external addresses.
The set up is:
- Outlook 2007/2010 on the clients, connecting to
- Exchange 2007 (SBS2008), which forwards to a Smarthost
- Mandrill. This processes the email, produces the NDR, and sends it back to
- Exclaimer Anti-Spam, running on the Exchange server. Logs show that the NDR is received & passed for delivery to:
- Exchange 2007. NDR disappears. It does not appear in the message tracking logs, and is not delivered to users inboxes, junk mail, deleted items or anywhere else.
I have tried:
- disabling Exclaimer anti-spam
- disabling all anti-spam features in Hub Transport
It seems that the message is getting dropped by Exchange on receipt - can anyone help track down where it might be going missing?