[exim] SpamHaus DWL config

SpamHaus released a whitelist on the weekend:

http://www.spamhauswhitelist.com/en/

In order to use their DWL service I stuck this in my Exim config:

acl_check_dkim:
  accept condition             = ${if eq{$dkim_verify_status}{pass}}
         dnslists              = _vouch.dwl.spamhaus.org/$dkim_domain
         set acl_c_whitelisted = true
         logwrite              = SpamHaus Whitelist (DKIM) $dkim_domain

Shortly afterwards I started receiving warning messages like this in my
mainlog:

2010-09-28 12:05:16 1P0Xzo-00047s-Pr dnslists domain
"_vouch.dwl.spamhaus.org" contains strange characters - is this right?

I'm guessing it doesn't like the underscore. Is it actually working but
just giving me a warning message, or is it skipping the check
altogether? How do I make this work?

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