How to configure Exim for autoreplying at domain level

Question

I have been hunting for an Exim advanced config for a scenario I have.

What would be the best way to achieve an auto-reply at domain level?

For example, there are 2 domains within WHM (domain1.com, domain2.com).

I want to set up an auto-reply for any emails sent to all email addresses under domain1.com whilst leaving domain2.com to operate as standard?

I know the standard config for a system-wide autoresponder would be:

ROUTER

uservacation:
  driver = redirect
  allow_filter
  hide_child_in_errmsg
  ignore_eacces
  ignore_enotdir
  reply_transport = vacation_reply
  no_verify
  require_files = /var/spool/exim/.vacation.msg
  file = /var/spool/exim/.vacation.msg
  user = exim
  group = exim
  unseen

TRANSPORT

vacation_reply:
  driver = autoreply

Is there a simple entry I can make to the Router config to stipulate the domains I want to use the autoresponder? Such as domains = domain1.com?