[Exim] treat a domain local if an alias file exists

Hi!

For my virtual domains, I have directors set up:
domain_aliases:
  debug_print                   = "domain_aliases for $local_part@$domain"
  driver                        = aliasfile
  optional                      = yes
  file                          = /etc/domain_aliases/$domain
  search_type                   = lsearch

That way, I have a single alias file per virtual domains. The virtual
domains need, however, be listed in local_domains as well to make exim
accept them as local. Manually maintained, this is a source of error.

Do I have any chance to make exim accept e-mail for domains where it has
an alias file for even if they are not explicitly listed in local_domains?

Greetings
Marc