Server Loads/hardware standards - recommendations

[Julian Field]

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Glad you find greylisting to be useful, I certainly did.

The next thing for you to install is milter-null from
http://www.snertsoft.com/sendmail/milter-null/

This will kill all the "your message could not be delivered" messages 
you get hundreds of. Completely.


Mevershosting.nl wrote:
> I just want to say WOW, We installed greylisting yesterday and the load
> on all our relay servers is around 1% 
> the avarage was around 10% 
>
> This greylisting gets a lot of spam out, people that worry about the
> delay, i have the delay set to 30 seconds and it works great,
>
> Thanx Julian for this tip.
>
> Richard
> Mevers
>
> -----Oorspronkelijk bericht-----
> Van: Julian Field [mailto:MailScanner at ecs.soton.ac.uk]
> Verzonden: dinsdag 17 oktober 2006 21:29
> Aan: MailScanner discussion
> Onderwerp: Re: Server Loads/hardware standards - recommendations
>
>
>
>
> * PGP Bad Signature, Signed by an unverified key: 10/17/06 at 20:29:20
> * text/plain body
> * Julian Field <Jules at jules.fm>
> * 0x1415B654 - Unverified(L)
> * PGP Bad Signature, Signed by an unverified key: 10/17/06 at 20:29:20
>
> Scott Silva wrote:
>   
>> Michael Kain spake the following on 10/17/2006 9:52 AM:
>>   
>>     
>>> Recently, I've gone from handling 40k messages /day to nearly
>>>       
> 30k/hour. 
>   
>>> The change has surfaced in the last month or so.
>>>
>>> My current setup:
>>> Dual P3 1.13
>>> 1GB Ram
>>> FC5
>>>
>>> Mail gateway running MS/clam/SA forwards scanned mail to internal
>>>       
> mail
>   
>>> server (when there's a problem, users hit send/receive and that
>>>       
> doesn't
>   
>>> cause an error..thus avoiding immediate call) I've used Julian's
>>>       
> clam/sa
>   
>>> install script (which is awesome), and read posts relating to new
>>> releases before upgrading/such.
>>>
>>> With spamassassin enabled, the batch list grows and grows, was up to
>>>       
> 95k
>   
>>> at one point.. disabling SA in MS cleared that out fairly quickly.
>>>       
> I've
>   
>>> wiped the SA/bayes temp files thinking bayes was backing up, however,
>>>       
> it
>   
>>> seems that is not helping.
>>>
>>> What I would like an opinion on is this... Am I trying to do too much
>>> with the hardware that I currently have?  Or do I put together a
>>>       
> bigger
>   
>>> beefier machine?
>>>
>>> -Mike
>>>     
>>>       
> You can make a huge difference to the amount of spam you have to process
>
> with 2 tools:
>
> 1) milter-gris
> 2) milter-null
>
> Number 1 implements grey-listing. There are a lot of discussions about 
> greylisting on the web, and a lot of people are very wary of it 
> initially. I was too. Then I ran a test with a handful of the fussiest 
> email users I have (I've got about 2000 users in total). I told them I 
> was implementing something new, but refused to tell them what, so they 
> would not have any pre-conceptions about it. They *all* loved it, and 
> none of them reported any problems at all. So I implemented it across 
> all of my users, who are very fussy Computer Science and Electronics 
> academics, as well as the students. That was about 6 months ago, since 
> when I have had *1* complaint, which I dealt with by adding them to the 
> whitelist for it.
>
> So my conclusion with greylisting is test it with some very fussy users,
>
> then roll it out to everyone.
>
> Number 2 implements back-scatter detection. Basically, what this does is
>
> get rid of all the "This message could not be delivered..." notices that
>
> weren't generated in response to your own users' mail. It doesn't throw 
> away all of them, so that if your users mistype an address, they still 
> get the error message from it. But all the delivery failure messages 
> generated by forged spam get killed.
>
> Between these 2, you will remove 80-90% of all the mail coming into your
>
> site, without losing any genuine real mail at all. This will make your 
> hardware go a hell of a lot further, and you will find you don't need to
>
> spend any money on new hardware at all.
>
> My MX servers used to just about cope. Then I implemented these 2 
> techniques and they now just tick along quite happily, getting very
> bored.
>
> Both of the above techniques can be done very easily in sendmail and 
> Postfix using the milters which are available from www.snertsoft.com. I 
> thoroughly recommend them to everyone.
>
> Jules
>
>   

Jules

- -- 
Julian Field MEng CITP
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