[Exim] Die Reverse Lookups Die

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Author: Will Morton
Date:  
To: exim-users
Subject: [Exim] Die Reverse Lookups Die
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    I've been experiencing some problems with some people reporting SMTP
timeouts connecting to our exim server (v3.33).


    After a joyous afternoon spent bolting packet sniffers onto various
parts of our network, I've determined that it's because they are
providing rfc821-breaching HELO arguments (HELO localhost or HELO
your.mail.domain), and so exim is doing reverse lookups anyway, as
specified in the config file.


    So, we're losing incoming mail, because if the offending server/client
has no reverse DNS mapping, the crappy thing SMTP times out before the
reverse DNS check finished. And then I get the PHB on my back :o)


    I notice that this is an issue discussed before (may wrap):


http://www.exim.org/mailman/htdig/exim-users/Week-of-Mon-20000306/017017.html

    is the post where Philip Hazel put the functionality in, to record
brain-dead servers. However I couldn't find any follow up.


    While if it were my personal mail server, I would concur with Philip,
and tell the offending parties to go off and get themselves a Real
Mailserver, this is a company machine and it's more important for us
that we don't drop mail.


    So I was wondering, is there an option along the lines of
'no_reverse_lookups_ever_ever_ever = true' that can be configured? A
compile-time option is fine, if necessary.


    Thanks in Advance


    W


--
    "Sometimes the Eloi really get on my nerves"


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