mouss escreveu:
> João Miguel Neves a écrit :
>
>> Charles Marcus escreveu:
>>
>>> On 2/8/2009, João Miguel Neves ([email protected]) wrote:
>>>
>>>
>>>> I recently enabled reject_unverified_sender in my postfix configuration,
>>>> but it seems like it fails when the server against which the sender is
>>>> verified uses greylisting. I've been getting log entries like (@ were
>>>> replaced by _AT_):
>>>>
>>>>
>>> You're not trying to verify ALL senders are you? This ia a really bad
>>> idea, and will get you blacklisted by a lot of providers, especially if
>>> you have high traffic .
>>>
>>>
>> Yes, I was. Thanks for the heads up. I don't have high traffic, but I'm
>> limiting the effect of SAV.
>>
>
> and how do you limit it? 71.66.121.221 is listed on zen.spamhaus.org
> (via cbl) and spamcop (as well as Barracuda BRBL, SORBS, ... etc). it is
> also a residential IP as can be seen from the rDNS (.res.rr.com).
>
Right now, I'm preparing my top 10 domains used in spam and enabling SAV
for those.
>>> You should only perform SAV against servers that YOU control, or at
>>> least have an agreement ahead of time with them.
>>>
>>>
>> That would mean that the most useful use of SAV is negated. Or is there
>> some prior arrangement that would allow me to do that to hotmail.com,
>> gmail.com, yahoo.com*?
>>
>> I'm going to reduce the target domains, but is there a known agreement
>> with MS, Google or Yahoo to use SAV against their servers?
>>
>
> No, and it won't help you anyway. spammers can easily use a valid
> address. and these domains have too many users that most addresses
> you'll test are valid! (did you never see the "sorry, this account is
> not available" when trying to open an account?).
>
Picking up some data from 4h when SAV was enabled from all users I get:
426 delivered emails
1742 rejected emails
985 rejects from sender checks from which:
302 were queued at the sender for SAV unverified results (*)
671 were queued at the sender for SAV undeliverable results
Maybe is SHOULDN'T help, but seems like a LOT of spam is still coming
from non-existing addresses (about 31% of the total email).
(*) this is the number that scares me a bit - it can be thanks to
greylisting, or possibly a loop caused by other server using SAV. I'm
checking into that.
Best regards,
João Miguel Neves
--
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