Resolved Error code: (26) DNS lookup failure

[Dewan D]

Hi Guys.

I have looked through the forums but the references I found sadly did not help.

Recently I have moved to a VPS with Plesk.
Everything seems to be setup fine, except some emails are not coming through when the SPF Filter runs.
Looking through the mail.log I have a few examples, since the text may vary a little but it generally seems to point to the same thing.

EXAMPLE 1
Dec 4 08:00:17 server1 spf filter[5574]: Starting spf filter...
Dec 4 08:00:17 server1 spf filter[5574]: Error code: (26) DNS lookup failure
Dec 4 08:00:17 server1 spf filter[5574]: Failed to query MAIL-FROM: Temporary DNS failure for 'abc.com'.
Dec 4 08:00:17 server1 spf filter[5574]: SPF result: tempfail
Dec 4 08:00:17 server1 /usr/lib/plesk-9.0/psa-pc-remote[40417]: handlers_stderr: DEFER
Dec 4 08:00:17 server1 /usr/lib/plesk-9.0/psa-pc-remote[40417]: DEFER during call 'spf' handler
Dec 4 08:00:17 server1 postfix/cleanup[5572]: 77D66E009C: milter-reject: END-OF-MESSAGE from a6-109.smtp-out.abc.com[x.x.x.x]: 4.7.1 Service unavailable - try again later; from=<000000@eu-west-1.abc.com> to=<me@myemail.com> proto=ESMTP helo=<a6-109.smtp-out.abc.com>

EXAMPLE 2
Dec 4 08:22:18 server1 spf filter[5701]: Starting spf filter...
Dec 4 08:22:18 server1 spf filter[5701]: Error code: (26) DNS lookup failure
Dec 4 08:22:18 server1 spf filter[5701]: SPF result: tempfail
Dec 4 08:22:18 server1 /usr/lib/plesk-9.0/psa-pc-remote[40417]: handlers_stderr: DEFER
Dec 4 08:22:18 server1 /usr/lib/plesk-9.0/psa-pc-remote[40417]: DEFER during call 'spf' handler
Dec 4 08:22:18 server1 postfix/cleanup[5699]: 35434E009C: milter-reject: END-OF-MESSAGE from 100000@eu-west-1.abc.com[x.x.x.x.]: 4.7.1 Service unavailable - try again later; from=<100000@eu-west-1.abc.com> to=<dd@tribalgames.co.za> proto=ESMTP helo=<100000@eu-west-1.abc.com>

I have tested ( with dig ) the nameserver with the websites giving a problem and they come back with correct result.
I am not sure how to go about resolving this issue, so I thought I would drop a message in here and see if anyone can help.

Thanks
DD

 

[IgorG]

Have you seen this KB article - https://kb.plesk.com/en/124056 ?
I hope it will help.

 

[Dewan D]

Have you seen this KB article - https://kb.plesk.com/en/124056 ?
I hope it will help.

Hi IgorG

I have already read that article and the solution does not apply since my SPF local rules is empty.

 

[UFHH01]

Hi Dewan D,

could you pls. post the content from "/etc/resolv.conf" ?
In addition, that you should consider to post your FQDN's with issues, so that people willing to help you have the chance to investigate your issue.

 

[Dewan D]

Hi Dewan D,

could you pls. post the content from "/etc/resolv.conf" ?
In addition, that you should consider to post your FQDN's with issues, so that people willing to help you have the chance to investigate your issue.

Hi UFHH01

First time posting here as I am a first time plesk user ( moved from cpanel ).
/etc/resolv.conf

# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
# DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
nameserver 10.255.255.1
nameserver 8.8.8.8

This is happening to dewandemmer.com, tribalgames.co.za and offthewallplays.com.

Thanks.

 

[UFHH01]

nameserver 10.255.255.1

??? This IP resolves to nowhere and should be removed from your configuration.

Second, you miss a "rotate" and "timeout" option in your configuration.

Consider to use the following:

nameserver 8.8.8.8
nameserver 8.8.4.4
nameserver 5.9.28.125

options rotate
options timeout:3

Pls. search for more ( additional, reliable ) DNS - nameservers, by searching with Google for example. But to be honest, you should be well with the above suggestion.

 

[Dewan D]

??? This IP resolves to nowhere and should be removed from your configuration.

Second, you miss a "rotate" and "timeout" option in your configuration.

Consider to use the following:

nameserver 8.8.8.8
nameserver 8.8.4.4
nameserver 5.9.28.125

options rotate
options timeout:3

Pls. search for more ( additional, reliable ) DNS - nameservers, by searching with Google for example. But to be honest, you should be well with the above suggestion.

Hi UFHH01

I put the above into the and I thought that had fixed the problem.
However I checked the logs this morning and the problem is still there.

 

[UFHH01]

Hi Dewan D,

Now we are going to have a look at the current SPF - entry for "abc.com":

v=spf1 mx ip4:204.128.192.17 ip4:204.128.192.36 ip4:204.128.192.43 ip4:192.195.66.26 ip4:192.195.66.28 ip4:192.195.66.36 ip4:205.159.75.76 ip4:205.159.75.77 ip4:205.159.75.78 ip4:205.159.75.79 ip4:139.104.67.248/29 include:spf.protection.outlook.com -all

... and we are going to see, that the total number of 10 DNS - requests are exceeded, which will result in a "tempfail". Depending to your mail - server settings for "SPF checking mode" ), the configured option will be triggered.

 

[Dewan D]

Hi. I am not entirely sure what fixed the problem, but I have removed the 10.255.255.1 ( which seems to have caused the 26 error ).
I am not sure why the tempfail was cause for a hard fail, however right now all is workign correctly.

Thanks for the help on this.