Re: Question about Qmail relating to MX retry processing

[Markus Stumpf <maex-lists-qmail@leo.org>]

On Sat, Nov 25, 2006 at 07:09:14AM -0800, Marc Perkel wrote:
> Yes, another trick I do is my highest MX record returns a 4xx on 
> everything that connect to it. Spammers try to hit the highest one first 
> thinking there's less spam filtering on it. As soon as the get the 4xx 
> error they go away and never come back. I get rid of about 350,000 spams 
> a day using that trick.

I really doubt that.
I agree that it helps to some extent, but I have been running such a
"trick" for about 2 years now. It rejected with 4xx at the end of the
DATA command at 2 longer distance MX hosts. This way one has the whole
message and I used that to feed it to a DCC system and build a SHA1 sum
of the message. The shortest distance MX is using greylisting.

I see tons of spammers connecting the whole MX set upwards and
downwards. So you probably force the spammers to 350000 useless
connects a day to your servers but I really doubt that you also get rid 
of those 350000 spam mails a day with that "trick".

    \Maex