I'm wondering if anyone has any experience with setting up a redundant Blocker setup. Our current setup (Blocker as primary MX and a fallback MX offsite) is redundant when it comes to not losing email. My main concern now is what will happen if the Blocker fails alltogether. Granted no email will be lost, but no email will be delivered either unless there is a manual intervention (switching fallback MX to deliver mail directly instead of via the Blocker).
Any hints or tips as to how to setup a redundant Blocker configuration?