[exim] local_domains by dns

Hi,

the exim docs do not seem to cover the topic of "how to build" a
local_domains list, they only cover the topic of "whats the syntax of a
list".

My actual problem is to build the content of local_domains from DNS IN
MX Records. The server shall only handle the domain as local,
if the mx is pointing to an address on the host.

Has anyone done this?

Can it be archived without perl script execution, which would be a
performance drop at least?


best regards,
Marius