lists: run mailman verp router before dnslookup

The mailman verp router handles remote addresses like dnslookup.
It needs to run before dnslookup in order to be effective, so run
it first.  It's only for outgoing messages, not incoming, so won't
affect the blackhole aliases we have for incoming fake bounce
messages.

Note that the verp router hasn't been used in about a year due to
this oversight, so we should merge this change with caution.

Change-Id: I7d2a0f05f82485a54c1e7048f09b4edf6e0f0612

playbooks/host_vars/lists.openstack.org.yaml

@@ -28,9 +28,6 @@ exim_aliases:
   women-of-openstack-owner: spam
   spam: ':fail: delivery temporarily disabled due to ongoing spam flood'
 exim_routers:
-  - dnslookup: '{{ exim_dnslookup_router }}'
-  - system_aliases: '{{ exim_system_aliases_router }}'
-  - localuser: '{{ exim_localuser_router }}'
   - mailman_verp_router: |
       {% raw -%}
       driver = dnslookup
@@ -45,6 +42,9 @@ exim_routers:
                                         c0::/10;ff00::/8
       senders = "*-bounces@*"
       transport = mailman_verp_smtp
+  - dnslookup: '{{ exim_dnslookup_router }}'
+  - system_aliases: '{{ exim_system_aliases_router }}'
+  - localuser: '{{ exim_localuser_router }}'
   - mailman_router: |
       driver = accept
       domains = {{ mm_domains }}