[Exim] verify if a domain exist

Is there any way to check if a domain exist in a ACL. I already try
the following :

   drop    sender_domains = !${lookup mysql {SELECT domain FROM domains \
                            WHERE domain="${sender_address_domain}"}}
           !verify        = reverse_host_lookup
           log_message    = ResolveTrap : sender_address=$sender_address
           message        = Not accepted from $sender_address because
$sender_address_domain do not resolve.

But "reverse_host_lookup" is to severe, when using that option many
little companies with their own mail server are blocked because their
ISP do not setup reverse correctly.

What I want is something that only check if the domain exists.

thanks

Dominic Germain
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Administrateur réseau / Network administrator
Internet Galilée

network-admin@???
1-800-561-3703 x226