exim -be
test.ex ${lookup dnsdb{test.ex}{$value}fail}
+s/lash.test.ex ${lookup dnsdb{s/lash.test.ex}{$value}fail}
txt=test.ex ${lookup dnsdb{txt=test.ex}{$value}fail}
a=black-1.test.ex ${lookup dnsdb{a=black-1.test.ex}{$value}fail}
xxx=test.ex ${lookup dnsdb{xxx=test.ex}{$value}fail}