>Kai Schaetzl wrote:
>> Matt Kettler wrote on Mon, 12 Dec 2005 17:12:50 -0500:
>>
>>
>>>There's all different degrees of trust and more ways to go about it than we
>>>can
>>>count here :)
>>
>>
>> I think simpler. Either I trust it or not, so either I use it or not. :-)
>>
>> Kai
>>
>
>Personally, I have yet to find a single RBL that's sufficiently accurate and FP
>free for me to begin to consider it for use as an MTA layer rejection criteria.
>
>But I consider using a RBL for MTA block an act of extreme trust.
>
>
>FWIW I'd require at least 5 nines of S/O to consider using an RBL as a block.
>Ideally I want it's FP rate to be on on the same order of magnitude as mail
>loss
>due to hardware failure on a reasonably redundant server (note: I'm talking
>probability of unrecoverable data loss, not percentage of uptime).
>
>
>The only RBL close to that accurate in the SA testing is XBL. No RBL is 99.999%
>accurate, Even XBL is only 99.994% (which rounds to a S/O of 1.000 in SA's
>STATISTICS-set1.txt, but if you re-extrapolate the raw numbers it is 272715
>spam
>hits, 14 nonspam hits, or S/O 0.99994 which is still only 4 nines, not 5)
>
Matt,
Do you have any idea (or even better, measurements) of what the FP
rate would be if you 4xx'd it instead of 5xx'ing - i.e. how many of those
FPs are corrected before the MTA re-delivery timeout period (yes, I know
that many sites use less than the recommended 5 days). Personally, I 450
the SpamCop list, and do occasionally delay "real" mail, but for my site,
I haven't yet found an FP (i.e. one that "never" gets delivered, not just
delayed, but SpamCop does "auto-remove" in a short period; most of the XBL
sources require that an administrator must "realize" he's been listed and
take some action, even if it is trivial - It requires knowledge of what to
do and/or at least monitoring log files, which we all know many sites do
not do). Also, I'm small enough that to receive 100K valid messages takes
many weeks.
Paul Shupak
[EMAIL PROTECTED]
