[exim] Using ADSP?

Hello,

I am just starting with DKIM and the design looks great. Having
just discovered ADSP, I wonder how to implement it.

The fine manual shows

dkim_verify_signers = $sender_address_domain:$dkim_signers

to run the ACL for the sender as well as for signers found in signatures.
Unfortunately, ADSP uses the From: header. Am I missing something with
this?

dkim_verify_signers = ${map{${addresses:$h_from:}}{${domain:$item}}}:$dkim_signers

It does not look like I can add multiple signatures, though, because
dkim_domain is not a list that sets $dkim_domain to each element,
expanding dkim_selector and dkim_private_key using that value and acting
upon it. Any other way?

Michael