[Exim] Expansion in ACLs

Hi,

Is there any variable which describes the "domain" in the "rcpt to:" command?
I want to use it in an acl.

thank you in advance,

Robert

PS:
check condition = ${if match {${lookup dnsdb {ns=$domain}}}{testdomain.com}{yes}{no}}
search_open: dnsdb "NULL"
search_find: file="NULL"
key="ns=" partial=-1

i guess the "key" shlod be "ns=mydomain.com" or somthing...