Casey T. Deccio wrote:
I am getting a lot of spam on my exim4 mailserver, much of which is logged with "no host name found for IP address ..." and "no IP address found for host ...". The acl_check_rcpt acl is mostly set with the debian defaults.
Not exactly what you asked, but maybe quite close: have you looked at greylistd (package). It is said to weed out 90 % of spam. Johannes