[Exim] ACL config to reject mail from non standard DNS maile…

I am trying to use Exim 4.30 ACL configuration to reject email that does
not conform to Internet DNS standards, on the theory that a lot of spam
is sent from zombie machines.

For instance,

  drop    ! verify = helo
          message = $sender_helo_name does not match name from reverse
lookup of $sender_host_address - $sender_host_name
          delay   = 59s

seems like a marvelous idea, until I saw

2004-02-27 14:11:24 H=(hotmail.com) [64.4.11.15]
F=<tunadave@???> rejected RCPT <mdm@???>:
hotmail.com does not match name from reverse lookup of 64.4.11.15 -
bay7-f15.bay7.hotmail.com


Is there a way to apply regular expressions to the verify = helo so that
the above will pass the verification process.

Would somebody be willing to share their Exim configuration file ACL
section of workable solutions to this problem ?

Or point me to some resources where this topic has been hashed out.

Thanks

mark