I have an exim server, running 4.69.
We are aware of the vulnerability, and due in part we are in the process of migrating to 4.75.
We have an "experimental" 4.75 email server set up, we want to set up our existing server to (preferably sometime in the ACL) check the email for certain conditions and if one is met, we want to relay the email to our experimental server for delivery.
How can I do this? Maybe I need to set up a specific transport for this purpose?