Block invalid NDR's
Posted on 2004-09-01
Does anyone know of a way to block invalid NDR's with Exchange 2000 - ie NDR's to emails not actually sent by a user within our organisation (typically when their email address has been spoofed by a spammer)? I don't want to block all inbound DSN's or even valid NDR's. I just want to block NDR's from external addresses in reply to emails that were never actually sent from within our organisation. I suspect that their may be a way to do this by doing some sort of reverse lookup on the originating domain in the NDR - to show that that the email that the NDR is a reply to did not genuinely originate from our domain? Is this possible?
Please help! One user in particular (who has obviously had his address spoofed by a load of spammers) is getting overwhelmed with NDR's for email he has not sent. What’s more they are forwarding all the erroneous NDR's to my boss :-(