SpamAssassian with FreeBSD and Big Mail Server

[Oliver Brandmueller]

Hi.

On Wed, Feb 23, 2005 at 12:15:22PM +0100, Randy Adamczyk wrote:
> do you receive a _lot_ of spam? if you are running into recource
> problems because of spam, you should look into greylisting:
> 
> http://www.greylisting.org/
> http://projects.puremagic.com/greylisting/whitepaper.html
> 
> greylisting for exim + spamassassin:
> http://greylisting.org/implementations/sa-exim.shtml
> 
> i use greylisting with postfix, spamassassin and virus-scanners with
> amavis-new. spamassassin hardly has any work to do since i implemented
> greylisting.

And when doing things greylisting, please try to see both sides.

Since people tend to see only their side, I will now describe the 
medium-sized-ISP side of things.

Well, everyday life. Spam of course also hit's our servers and due to 
legal things we cannot just filter every incoming mail. Queues are 
around 5000 mails. That's OK with our hardware.

Then, one day, someone invented greylisting. Great idea. Since 
especially universities and other organizations like this have adopted 
it, his means that quite a lot of mails go to servers with greylisting. 
Queues have grown since then. 10000 per server average is what we see 
now. The problem here is, that in theory the server tries again after 5 
minutes and gets the mail delivered. The real side of the problem is: 
The bigger the queues are, the more time it takes until you come up with 
the same mail again. So mail takes not 30 seconds to arrive,not 5 
minutes like greylisting theory, but maybe half an hour. That's already 
a value some customers complain about. Now people without the slightest 
idea what they are doing start to implement greylisting. They get the 
connection from 123.123.123.1 the first time and send their temporary 
error. Fine. The queue runner on 123.123.123.7 picks up the mail next 
time. Temporary error, because the .1 is currently allowed to send the 
mail. OK, second temporary error. Mail stored in lower prio, next 
delivery attempt in one hour. And so on.

Greylisting makes a lot of trouble at big sites. And mens longer and 
sometimes very delivery times for mail.

Great idea, yeah, spread that to the world, maybe the day will come, 
when snailmail is faster...


- Oliver


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| Oliver Brandmueller | Offenbacher Str. 1  | Germany       D-14197 Berlin |
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