[exim] Preserve certain headers, drop the rest

Hi,

I cannot find the option to keep a given set of headers and drop the rest, similar to what is available in Postfix for instance (with the header_checks).

We relay emails from various remote locations (which are using various mail setups). It is impossible to anticipate the variety of headers each individual MTA has added (custom x-headers and such) and we need a clear and consistent outgoing mail header setup. So ideally we would retain a predefined set of headers and drop the rest.

However, I cannot find a way to do this in Exim. Maybe someone has any pointers in the right direction?

Many thanks!
Rigu