Re: [exim] Sender callout verification on BATV signed addres…

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Author: Mike Cardwell
Date:  
To: Exim Users List
Subject: Re: [exim] Sender callout verification on BATV signed addresses
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 can reduce the chance to get listed on a RBL by
> using spf, whitelists, etc .. (calloouts also have it's own cache)


True, that is an additional way to reduce the chance further.

> we have been using callouts since they exist without ever being
> blacklisted


You don't want to advertise that fact on mailing lists like this, or
your listing status might get changed.

--
Mike Cardwell
(https://secure.grepular.com/) (http://perlcv.com/)