[exim] Using readsocket for ratelimiting?

Has anyone considered, or already made a rate limiting ACL using readsocket?

Besides writing a simple daemon, I don't see any reason not to try this out.
I envision sending various data to the daemon, like sender IP, recipients,
sender address, then getting a pass/fail from the socket depending.
On that pass fail, I guess you could wrap it in a defer or reject ACL,
however you want.

This way, the rate limit database doesn't need to reside on a single box,
the socket daemon could use memcache or a proper DB.

Any thoughts?

--
Brent Jones
brent@???