[exim] headers_add and message id

Hello,

Due to extensive problems with AOL I would like to start adding a custom
header for all outgoing emails that would put the message ID information
into it, something like that:

headers_add = "Feedback: 1HoHwW-0007Of-5J"

Is this possible and which variable would I have to use to insert message
queue ID into message header?

So for I am using headers_add = "X-Feedback: $local_part" with
remote_smtp transport but AOL sheepishly cuts that out and I am no able to
check who of their brialliant customers marks our messages as spam instead
of opting out.

If there's a better solution, do let me know. Thank you!

--
Zbigniew Szalbot