[Exim] host reject config problem

Exim 3.16

My configuration is giving me trouble. Today I started getting a lot of
errors in my reject log: (failed to find host name from IP address) and
we seem to be bouncing 5 times the usual amount of mail.

1st, I like to know what option in my conf file is causing this. I
suspect it is the host_reject_recipients but I would like to be able to
confirm this. I have removed host_reject_recipients for now and it
does seem to have stemmed the flow.

2nd, Can I use a mixture of ip addresses and domain addresses in a
host list? I want to make sure certain domains and/or IP addresses
that spam us are rejected. I have found that the ip address can
change sometimes but the domain generally the same. I have been
using a list like the one below, is it a valid host list?

host_reject_recipients = /path/to/file/exim/host_recipients

# host_recipients
*.somedomain.net.ar
211.92.129.184/32
*.anotherdomain.net


Thanx.
Dp.


~~
Dermot Paikkos * dermot@???
Network Administrator @ Science Photo Library
Phone: 0207 432 1100 * Fax: 0207 286 8668