On Mon, 2010-11-08 at 11:38 -0800, Marc Perkel wrote:
> I'm wondering how to do something tricky, it's perhaps slightly off topic.
Indeed it is - you're after a layer 7 proxy for SMTP which is doing DNS
lookups.
Have you tried NGINX?
http://wiki.nginx.org/NginxMailCoreModule
I've no idea whether or not you can make it do what you require but it
looks slightly plausible.
Graeme