[Exim] How to stop reverse DNS lookup?

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Hello,

I am running an Exim server for many different domains and client IP addresses.
I am using Pop before Smtp auth with a MySQL database, which is working fine.

The only problem is when the clients try to send an email and their machine IP address does not have a DNS Host name associated with it, due to either a misconfiguration or its deliberate. They get the error "Failed to find host name from IP address".

I have host_lookup commented out. The client IP address is in my host_accept_relay list, but it still tries to find the host name.
The only workaround I have found so far is to put a bogus entry in my /etc/hosts file for the clients IP address.

How can I stop Exim from trying to find the host name for a given IP address? I've searched throught the manuals and FAQ and could not find this particular problem.

Thanks
Chris

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