Over the past few weeks, I noticed that Users have been receiving strange emails, namely NDRs (Non Delivery Reports), stating that a message that they allegedly sent did not reach the recipient. This recipient is an address that user has not probably never heard of, and User definitely did not send any email to that address.
I think this is a new spamming technique, whereby to draw users attention and bypass spam filters, the spammer sends the message as an NDR (Non Delivery Report). In other words, my user did not send the original email to that unknown recipient. The message succeeds in bypassing my spam filter, and sure enough, it is drawing the attention of the recipient (in this case, users) to open the undelivered message. For my network I am using Mail Essentials version 11 which is installed in my ISA server.
My schenario is Internet--ISA(ME)-Front End server-Back End(Exchange cluster).
Please suggest me what configuration do I need in Mail Essentials to detect and delete those e-mail or I need to install anything else for detecting and deleting those e-mail.