I've got two mail servers - old and new. I want to migrate mail bbut I need both servers to receive and store emails until I work out the bugs out of the new system.
If I add another MX record and set the priority to both of them it will randomize the process. I do not want load balancing, I want for every message received by the DNS to be mirrored and routed to both mail servers.
How can this be done?