Re: [exim] Integrating URI Blacklists into Exim

Dave Lugo wrote:
> On Thu, 18 May 2006, Brent Clark wrote:
>
>> Silly question, cause you probally know / do it, but are you using
>> sender / callback verification.
>>
>>
>
> Nope.
>
>
>> I find that 90% of my spam blocking gets handled by this, and then after
>> that im reliant on Dspam.
>>
>>
>
> I'm glad it helps you, but for the folks[1] with domains that
> are heavily forged by spammers, the callbacks themselves are
> a additional DoS they have to deal with.
>
> [1] not me, but others I know.
>

Not if it's done right. Exim caches results avoiding repeated calls. And
I do a trick with dictionary attacks where I will return a DEFER on an
IP address for a 5 minute period if they commit certian sins that get
their IP on my 5 minute defer lists.