[exim] Random sender callout caching WAS conducive.org

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Author: Stuart Gall
Date:  
To: exim users
CC: David Woodhouse, W B Hacker
Old-Topics: Re: [exim] conducive.org
Subject: [exim] Random sender callout caching WAS conducive.org

On 18 Oct 2006, at 18:11, Stuart Gall wrote:
<snip>

>
> I checked the docs, they are unclear about the negative random callout
>
> verify.c
> says
>    /* If a previous check on a "random" local part was accepted, we
> assume
>      that the server does not do any checking on local parts. There
> is therefore
>      no point in doing the callout, because it will always be
> successful. If a
>      random check previously failed, arrange not to do it again, but
> preserve
>      the data in the new record. If a random check is required but
> hasn't been
>      done, skip the remaining cache processing. */

>
> It is definitely cached, but my C++ is not up to figuring out which
> cache is used.
>


Looking a bit deeper and struggling with the C++ I believe that the
random check goes in the domain cache and so would be subject to the
domain-cache-timeouts

That is OK for positive expire, in fact I dont see that domain
positive expire is used for anything else.
Positive on mail from :<> is useless to cache because you still have
to do the callout and you will discover implicitly if the policy has
changed.
Default 7d by the way, one random address tried every 7 days to
domains that have a catchall account.

But domain negative IMHO the random user should not be tied to the
refusal to accept mail from: <>

I am quite happy to have 3h on refusal to accept mail from:<> but a
site that does not have a catchall account I would like to recheck
about once a week at most.

OTOH
>Domain records expire when the negative expiry time is reached if

callouts cannot be made for the domain, or if the postmaster check
failed. Otherwise, they expire when the positive >expiry time is
reached. This ensures that, for example, a host that stops accepting
“random” local parts will eventually be noticed.

Does this mean that domain_callout_positive_expire controls both the
positive and negative cache entries for random local parts ?

That is quite good then, if true, I suggest that it is specifically
mentioned in 39.34
Stuart.


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