[exim] deny.senders using partial match

Hi folks.

in acl_check_data I have the following:

  deny    senders = /etc/exim/lists/deny.senders
          log_message = $sender_address listed in deny.senders

as most people do. What I want to know is how can I add a similar rule using
substring matching? I want to be able to block senders such as

O2 billing <random.email@address>
HMRC <another.silly@???>
Halifax <somewhere.in@poland>