Heads up for spamhaus.org problems

[DAve]

DAve wrote:
> Richard Potter wrote:
>> On Mon, Aug 20, 2007 at 11:34:05PM +0200, Alex Broens wrote:
>>
>>> On 8/20/2007 11:22 PM, Tim Boyer wrote:
>>>> On Sun, 19 Aug 2007 22:02:01 -0400, Richard Potter 
>>>> <rpotter at rpcs.net> wrote:
>>>>
>>>>> On Mon, Aug 20, 2007 at 12:34:23AM +0200, Raymond Dijkxhoorn wrote:
>>>>>
>>>>>>> Just doing a routine check here, and I have a few mail servers 
>>>>>>> misbehaving. It
>>>>>>> *appears* sendmail dnsbl to zen.spamhaus.org is timing out, and 
>>>>>>> causing mail
>>>>>>> delivery delays, or none at all.
>>>>>>>
>>>>>>> I'm going to discontinue spamhaus, and see what happens.
>>>>>> Buy rsync from them. Most likely you fire a lot of lookups on 
>>>>>> their servers and they started to ban high volume mailservers some 
>>>>>> time ago.
>>>>>> We have seen this in a lot of places allready.
>>>>>>
>>>>>> May i ask how much mail are you processing daily?
>>>>> Thanks for the reply Raymond.. I wasn't aware they were doing that. 
>>>>> These
>>>>> are low volume servers, less than 2,000 messages per day. Does that 
>>>>> count
>>>>> as "high volume" to spamhaus?
>>>>>
>>>>> Richard
>>>> "Use of the Spamhaus DNSBLs via DNS queries to our public DNSBL 
>>>> mirrors is free
>>>> for low-traffic mail servers serving less than 100 users. Use of the 
>>>> Spamhaus
>>>> DNSBLs by commercial or corporate networks, ISPs and ESPs, requires a
>>>> subscription to Spamhaus's Data Feed service."
>>>>
>>>> I'd be shocked if 2,000 messages per day counts as high volume.  
>>>> That's 20
>>>> emails per person per day.
>>> no need to be shocked :-)
>>>
>>> Spamhaus can't block your mail server from doing queries - it blocks 
>>> your DNS' access to the root zone - so if you use a DNS which is 
>>> querying Xmillion queries/day and your server is only doing 10000/day 
>>> then the rest of the X/million+your 10000 makes he count which rates 
>>> a block.
>>
>>
>> You are exactly right. I was told that off list. I switched the two 
>> boxes to an alternative DNS server, and spamhaus worked again.
>>
>> I'm not sure why I didn't figure that out on my own. I actually 
>> knew/should have known that. It was Sunday, and I might have had a few 
>> beers! :-)
>>
>> Richard
> 
> Are you using a caching server? Possibly it's not the 2000 queries a day 
> they block, but the 10,000 needlessly repeated queries from the same DNS 
> server.
> 
> DAve
> 

I am *not* suggesting spamhaus blocks are your fault. When I re read my 
response it looked kinda mean the way I said it. I apologize if it 
appears that way.

I do suspect spamhaus gets a large number of queries from non-caching 
servers. The use of a DNS cache is faster for you, less load for them, 
everyone wins.

DAve


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