[exim] Discard mail to certain recipients if the subject mat…

Hi list,

I need to discard mail from a known address to certain recipients IF the
subject matches a known string. I've tried to add

  discard message = The $sender_address is prohibited to send commit
notifications to these recipients
          senders       = <known address>
          recipients    = <recipient 1> : <recipient 2>
          condition     = ${if match{$h_subject:}{Commit}}

to acl_check_data section of exim.conf but got an error:

... temporarily rejected after DATA: cannot test recipients condition in
DATA ACL

What would be the correct way to accomplish this?

TIA