--On 14 May 2009 12:50:19 +0100 Mike Cardwell
<exim-users@???> wrote:
> David Saez Padros wrote:
>
>>>> we use callbacks on a similar way, we do not do the callback
>>>> if the incoming mail passes spf, dkim is not used to prevent
>>>> callbacks because we do callbacks at RCPT time and dkim needs
>>>> to reach DATA, we also use whitelisting to prevent callouts too
>>> Can I ask why you don't do the call backs in DATA then? If I were to
>>> use callbacks, personally I'd want to make sure they were run at the
>>> very end of my spam filtering to reduce the likelyhood of my server
>>> being listed on an RBL for backscatter...
>>
>> it takes less resouces to do the callback at rcpt than at the very
>> end of the spam filtering
>
> You could argue that using N lumps of somebody elses resources is worse
> than using 10xN lumps of your own. Especially if the 10xN is going idle,
> which on many systems it is...
You'd not be using any lumps of their resource if they used SPF, and gave
you a fighting chance of recognising when email was coming from their
system.
--
Ian Eiloart
IT Services, University of Sussex
01273-873148 x3148
For new support requests, see
http://www.sussex.ac.uk/its/help/
