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Re: 7. BCP - Mail Administrators: Checking HELO (was: [Asrg] 0. General - Administrative - for M. Wild)

2003-09-02 06:41:19
On Sun, Aug 31, 2003 at 03:49:24AM +0200, Brad Knowles wrote:
At 8:04 PM -0500 2003/08/30, Steven F Siirila wrote:

We have seen about 1,200,000 different IP addresses connecting to us in 
the
past six months and we block about 1,000,000 SMTP connections on our MX
servers every week on average.  What other stats would be of interest?

      What's your breakdown of why those connections are blocked?  How 
many unique blocks are due to which blacklist?  How many unique 
blocks are from lack of rDNS?  How many unique blocks are there by 
domain-based blacklist?  How many unique blocks are there due to 
other techniques?

I will try to post some data soon.

      I assume that once you have a positive response on one of those 
checks, you reject the connection and you don't bother trying the 
other checks as well.  Could you re-process your data to apply all 
checks to all IP address/envelope sender/recipient combinations, to 
see where certain blocks might overlap?

No, we reject on potentially multiple reasons.  Dynamic IP, no rDNS when
rDNS is required, known spammer, known open proxy, known open relay, etc.

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