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From: Andrzej Adam Filip on 16 Apr 2008 13:26
Grant Taylor <gtaylor(a)riverviewtech.net> wrote:

> On 04/16/08 10:44, Andrzej Adam Filip wrote:
>> What is you opinion about using different GreetPause for
>> a) DUL addresses (synamic IP ranges)
>> b) worse reputation nets [e.g. L2.APEWS.org lists "the worse
>> half" of the Internet]
>
> Personally I do not do that, but I see no problem with doing that. I
> think doing such would be a PITA to manage. If you want to update
> your (what will be complex) GreetPause configuration go for it.
>
> Though I doubt that you will see much ROI for your trouble. I think
> it would be better to set your GreetPause low and start raising it
> while watching how many times it is triggered. You decide if you want
> to alter it based on location or not. Keep in mind that GreetPause is
> intended to cause sending systems to wait for your server's HELO
> *BEFORE* the client sends its HELO / EHLO to your server. So if there
> is a GreetPause that is sufficiently long enough to catch senders that
> are not pausing (or are pausing in between commands regardless of
> reply) I don't think raising it much higher will catch any (vary few)
> more systems that are actually waiting for a reply and following SMTP
> state like they should be. In short, if the sending system is willing
> to wait for your HELO, I don't think it will matter if the wait is 1
> second or 30 seconds or something else as the client *IS* (most
> likely) following proper SMTP state which is what GreetPause is
> intending to catch (those that are not playing by the rules).

Setting GreetPause involves balancing between the gain
(detecting "inpatient" sources of most likely spam)
and pain (blocking *some* legitimate sources).
Some people recommended even using *very long* GreetPause delays,
IMHO *TOO* long to make them fit for "good reputation nets.

I merely suggest that it may be worthwhile to evaluate the best
"balance point" separately for the better and the worse halves of
the Internet.

--
[pl>en Andrew] Andrzej Adam Filip : anfi(a)priv.onet.pl : anfi(a)xl.wp.pl
The 11 is for people with the pride of a 10 and the pocketbook of an 8.
-- R. B. Greenberg [referring to PDPs?]
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