Hello
We have a setup with a simple internal Exchange 2010 environment. We journal all of our messages into Mimecast Cloud.
We have recently introduced an internal security appliance that we have setup to check all mail for any threats, etc. To send all mail to this new appliance we have setup a transport rule to BCC all messages to this appliance. The appliance has been configured to receive email messages on a subdomain of our main domain name. The subdomain name is not registered publically as it is only used internally, and it means we can setup a simple connector to send to this domain.
The problem is that all email sent to this appliance is also being sent to Mimecast journal. Because the domain name is not configured externally, we are starting to see a lot of NDRs occurring.
Ideally we would like to stop the BCC'd mails being sent to Mimecast but cannot see a way to do this with a transport rule? Is there any other way to stop this from occurring? One suggestion was to add the internal email address as an additional Journal address so all mails are journaled to Mimecast and the appliance?
We asked Mimecast to add our spoof domain name into our tenant. This has not stopped NDRs as we get 5.7.1 unable to relay errors.
Thanks