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How to disable "reverse dns check" in Exim 4?

Posted on 2004-10-06
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Last Modified: 2008-01-09

Hi all,

We have many problems with clients not receiving mails form misconfigured servers because Exim checks if the Reverse DNS is valid.

For example:
2004-10-07 02:05:21 no host name found for IP address 200.198.91.130

How can I disable this feature?


Regards,
Luiz
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Question by:ipsystems
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Expert Comment

by:The--Captain
ID: 12246024
>How can I disable this feature?

Are you sure you want to?  Some large email sites require some answer to DNS PTR queries before email is accepted - I am guessing that you are avoiding a significant amount of spam by the inclusion of the feature.  Even my cable ISP has it together enough to have reverse DNS entries for all its IPs (including my own).  Do you really want to accept mail from folks who are even more clueless than the average cable ISP?

Cheers,
-Jon
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Author Comment

by:ipsystems
ID: 12246035

Hi Jon,

Is a big problem, many customers has misconfigured servers and complain with me that can't receive messages from their friends or customers.

If its possible to create a IP "Whitelist" for Reverse DNS will be greate, is it possible?

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Expert Comment

by:Pushpakumara Mahagamage
ID: 12246056
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Expert Comment

by:Pushpakumara Mahagamage
ID: 12246066
To enable reverse DNS lookups or define an external DNS server list, complete the following steps:

1.
 Start System Manager. If administrative groups are enabled, expand the administrative group in which the server you want to use is located.
 
2.
 In the console tree, navigate to the Protocols container. Expand Servers, expand the server you want to work with, and then expand Protocols.
 
3.
 In the console tree, expand SMTP. Right-click the virtual server that you want to work with, and then select Properties. The default SMTP virtual server controls message delivery for the default domain.
 
4.
 In the Delivery tab, click Advanced. This displays the Advanced Delivery dialog box shown previously in Figure 13-7.
 
5.
 To enable reverse lookups, select Perform Reverse DNS Lookup On Incoming Messages. To disable reverse lookups, clear this option.
 
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Author Comment

by:ipsystems
ID: 12246095


Hi Push,

My problem is in Exim under Slackware, not Exchange..


Cheers,
Luiz
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Expert Comment

by:Pushpakumara Mahagamage
ID: 12246102
yes yes now i c...Sorry...

Push
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Expert Comment

by:Pushpakumara Mahagamage
ID: 12246132
did you read this article....coz i'm play with exchange 2000

i think this much help you...

http://www.exim.org/exim-html-4.20/doc/html/spec_7.html


Cheers,

Push
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Expert Comment

by:Manpreetbr
ID: 12246473
Disabling the Reverse DNS lookup makes email reception faster looks more friendly . I do use exchange not aware of Exim architecture but sure you will remain missing emails until you disable it . There are security reason/misconfigured some people don't allo the lookup one or other way .

I support the above comment to support the spam emails by putting resverse DNS lookup .

Thanks
Manpreet Brar
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Accepted Solution

by:
The--Captain earned 500 total points
ID: 12252334
>If its possible to create a IP "Whitelist" for Reverse DNS will be greate, is it possible?

That should be as easy - just set up a local DNS server, configure reverse DNS entries for all your "whitelist" hosts, point your mail server at your local DNS, and you should be all done.

Cheers,
-Jon
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