[Slackbuilds-users] Spamassassin from SBo - broken DNS RBL filtering?

Sebastian Arcus s.arcus at open-t.co.uk
Sat May 20 19:27:01 UTC 2017

On 17/05/17 18:17, Sebastian Arcus wrote:
> On 17/05/17 16:31, Franzen wrote:
>> On 17.05.2017 16:18, Sebastian Arcus wrote:
>>> I have been chasing this issue on-and-off for months, and spent a lot of
>>> time the last few days on it. I run several Slackware servers with
>>> Spamassassin on them, and I  noticed a while ago that some don't use DNS
>>> blocklists.
>> Maybe your are using the providers nameserver, beside a lot others, so 
>> the providers nameserver itself may be blacklistet because of too much 
>> reqeuests, and therfore gets no(or only sometimes) answers from the 
>> dns blackalist severs. This also happens if you are using google's dns 
> Sorry, I should have mentioned it in the original post. I am running 
> Bind locally in caching/recursive mode. Also, if that would have been 
> the problem, the queries get flagged as blocked by SpamAssassin in the 
> message report - so it is quite soon obvious what is going on. I've had 
> this in the past, before configuring Bind. What I am describing is a 
> silent issue - no errors, no messages about queries being blocked. And 
> that is why it took me a while to realise it was a problem, because if 
> there is no mention in the spam report of dns rbl's - the assumption 
> would be that the dns queries returned nothing - not that they are not 
> working altogether. Only by passing the same known spam message through 
> SpamAssassin on different servers did I realise that the dns rbl's 
> weren't functional.

A follow up on this. I've tested the issue on some more machines, and it 
seems that it is the Spamassassin version which is the problem. On none 
of the machines I had with 3.4.1 dns rbl's were working. I have one 
server with 3.4.0 and dns rbl's *are* working on it. I have upgraded the 
7 servers I had with 3.4.1 to 4.0.0 unstable and they all work fine now. 
They were all Slackware 14.2-current in various states of "freshness" - 
up to one year old. So if you have Spamassassin 3.4.1 installed on a 
Slackware box, you might want to check that the dns rbl's are really 
working - as there were no error messages anywhere on mine. Oh, and for 
the sake of clarity, I kept all the configs as they were - so it wasn't 
a config problem.

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