It's also not just enough to ping the higher priority MX peers because the spam checker might be running on the primary MX only so it would only receive delayed mail from the backup MXes once it was back up.
Perhaps something like:
- a higher priority MX is up - the mail was delivered from a secondary MX with little or no delay
My concern was primarily for the secondary, where you don't know the delay until you forward. Are you saying that the first rule runs on the secondaries, and the second rule runs on all but the lowest-priorty MX?
I've got a secondary which receives very little traffic for itself, and virtually all of the remaining traffic is spam destined for a primary elsewhere. It's running SA from MIMEDefang, configured to reject anything scoring 10 or more. Giving it a rule like the one proposed here would allow it to reject more instead of queuing it to the primary.
