[Exim] SPAM from DHCP users

This message is in MIME format. Since your mail reader does not understand
this format, some or all of this message may not be legible.
--
[ Picked text/plain from multipart/alternative ]
Is there some how that I can use exim to verify the host sending a mail in
an attempt to block spammers.
They connect to my mail server and type something like.

Helo compuserve.com

Yet their address is adsl1.earthlink.xxx.xxx.xxx.xxx


--