Does anyone know how to make postfix avoid getting into an endless loop of errors when a remote mx server resolves to 0.0.0.0 ?
The problem sounds exactly like that described here: mail loops back to myself | postfix but i'm looking for a fix, as this makes postfix use 100% cpu.
Hoping this is a fairly simple tweak to the postfix config.
What version of Postfix are you running? If it isn't recent, try to upgrade to the latest stable version as there are advanced checks if there's something wrong with DNS.
I've had this problem but with an old application handling reverse DNS names badly, I used a small DNS filter proxy to remove bad requests. This is the same technique with twisted and python to filter A records. I only had about 100 dns request per second but had no performance issues.
The day after people told me I should have used LD_PRELOAD instead. :-) But my C isn't that great.