The Exim Specification doc says:
"If an attempt to look up the name of a host from its IP address
fails because there is no PTR record in the DNS, Exim
takes a hard line by default. "
Which, to me means that any host whcih doesn't have a reverse DNS entry will
get rejected by default. Now, I've been experimenting with my Exim config in
order to reject mail from certain hosts, so I put the following in the Main
Configuration secion:
sender_host_reject = lsearch;/usr/exim/tables/banned_sites
Where "banned_sites" is a list of host names to ban. Before I made the
change I'd only get one or two entries per day in the reject log, but
afterwards I got a number of rejections such as:
1999-03-19 12:29:39 connection from [111.222.333.444] refused
(reject host) (failed to find host name from IP address)
which is what I thought was supposed to happen by default. However, If I
change the config to have the following:
sender_host_reject_recipients =
lsearch;/usr/exim/tables/banned_sites
recipients_reject_except = postmaster@???
I get
1999-03-19 16:07:45 recipients from [999.888.777.666] refused (host)
Am I missing something, or is rejection of mail from IP addresses without
names dependant on there being a sender_host_reject or
sender_host_reject_recipients being present in the config file?
Paul Walsh
Senior Systems Programmer, Information Services,
University of Central England, BIRMINGHAM B42 2SU, UK
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