[Pkg-exim4-users] Secondary MX with virtual domain config

[x_debian-exim4-users_x at nospam.pz.podzone.net]

Hi,

I am trying to configure exim for so called 'virtual' domains, but
with a primary/secondary MX scenario.  In fact I'm not so sure this is
strictly correct usage of primary/secondary terminolgy but I hope it's
clear.

The stock solution appears to be the "vdom_aliases" router (below), as
variously quoted in howto's and internet postings.  However afaict,
this only caters for single server operation and my attempts to morph
this to work satisfactorilly on a secondary MX have failed so far.

I have previously used the hubbed_hosts router (below) on the
secondary MX, together with callout to the primary to check for valid
recipient.  This doesn't work so well I think if the primary MX is
down.

So I think the solution is to modify the hubbed_hosts router so that
it will consult a local configuration (as the vdom_aliases router
does) to validate the recipient addr.

The primary MX would then run the vdom_aliases router as per normal,
with it's local configuration of /etc/exim4/virtual/... files.

My efforts to figure this out have so far not come to much.  I'm
hoping someone can point me in the right direction please?

I'm happy if the solution requires files to be synched between MXs, or
a hybrid solution where /etc/exim4/virtual/... is first used for
vaildation and /etc/exim4/hubbed_hosts is then used for routing.

-- 150_exim4-config_hubbed_hosts --

hubbed_hosts:
  debug_print = "R: hubbed_hosts for $domain"
  driver = manualroute
  domains = "${if exists{CONFDIR/hubbed_hosts}\
                   {partial-lsearch;CONFDIR/hubbed_hosts}\
              fail}"
  same_domain_copy_routing = yes
  route_data = ${lookup{$domain}partial-lsearch{CONFDIR/hubbed_hosts}}
  transport = remote_smtp

-- 350_local-config_vdom_aliases --

vdom_aliases:
      driver = redirect
      allow_defer
      allow_fail
      domains = dsearch;/etc/exim4/virtual
      data = ${expand:${lookup{$local_part}lsearch*@{/etc/exim4/virtual/$domain}}}
      retry_use_local_part
      pipe_transport   = address_pipe
      file_transport   = address_file
      no_more

My references on this have so far been the (Red) Exim book, and -

http://www.debian-administration.org/articles/140

http://wiki.nerdylorrin.net/wiki/Wiki.jsp?page=EximVirtualDomains

Thanks in advance for any help or advice received.

Charlie