[Exim] smartuser director

Hi,

i can't figure out the syntax for a conditon check in the smartuser
director.

smartuser:
condition = "${if {{match {$original_domain} {mydomain.com}}}}}"
driver = smartuser
new_address = all@???

the error maessage

2000-12-04 15:14:32 142vLM-0001Oa-00 failed to expand condition"${if
{{match {$original_domain} {'mydomain.com'}}}}}" for smartuser director:
"{match
{mydomain.com" is not a number

thx for help

Tom Fischer