> On Jun 3, 2016, at 6:48 AM, Rob Maidment <rmaidm...@gmail.com> wrote:
>
> The SMTP proxy can add an X-header indicating where the message should
> be routed.
> In the upstream Postfix instance I can configure header_checks to
> check for the X-header and return a FILTER response based on the
> header value using a regex.
A filter action via header_checks will do what you want. If
the FILTER re-routes mail to a remote server you're fine. If
the filter ultimately re-queues mail on the same system, you'll
need to make sure that the header check does not cause a loop,
by suppressing it for re-queued mail, or stripping the header
somewhere along the way.
--
Viktor.
