I have a strange problem where the NDR messages sent by my Exchange internally are being caught by GFI MailEssentials anti-spam module.
Can someone please explain me what is the nature of Exchange NDR ? GFI MailEssentials anti-spam module can only process SMTP traffic. Does it mean they are SMTP messages ? GFI anti spam is suppose to only catch messages coming from outside, yet, somehow, its also affecting Exchange non delivery reports.