Re: [Exim] failed to find host name from IP address

On 8/18/2004 17:24, "Suresh Ramasubramanian" <linux@???> wrote:

> Hochstrasser Benedikt wrote:
>> Today I see in my logs an increased number of rejections because of
>> "failed to find host name from IP address". While this is perfectly fine
>> when dealing with spammers I have the uneasy feeling that exim sends a
>> reject upon every kind of DNS failure. (some of the DNSes I tried
>> managed to resolve the IP in question while others didn't).
>>
>> Or can someone confirm that eg. upon DNS time-outs exim sends a 451 (?)
>> temporary error message instead of a 550?
>
> exim wont do this unless you configure it to

Exim will comment about the failure in the log. But actual rejection is
something one has, as Suresh says, configured Exim to do.

We create a header for incoming hosts which don't reverse, but we don't use
Philip's draconian but correct requirement about forward and reverse lookups
matching: too many hosts broken according to that, and we aren't able to
reform the Internet (we didn't even have much luck reforming the State of
Washington, which attempts, somewhat feebly in the old days...better
now...to provide name service for the state's schools).

We let the users use the headers two ways: 1. tell us to drop messages
which contain it, or 2. use suitable MUA filters they design.

We can't even use Exim's lookup capabilities in an ACL to do this, because
of problems resulting from some DNS errors...we call a daemon we wrote to do
it the way we want.

--John