Re: [Exim] Sender verification... long-term temporary failur…

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Autor: Alan J. Flavell
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A: Exim users list
Assumpte: Re: [Exim] Sender verification... long-term temporary failures should be considered permanent.
On Thu, 30 Oct 2003, David Woodhouse wrote:

> On Thu, 2003-10-30 at 18:51 +0000, Alan J. Flavell wrote:
> > I've no expertise with intermittently-connected MTAs,

[...]

> It's Demon Internet's mail host -- it'll try sending mail by SMTP
> whenever I reconnect (and some other times besides although
> bizarrely not when I ETRN) and will keep it for a _long_ time
> without bouncing it. It's _designed_ for intermittent connections.


Hence my disclaimer ;-)

> Yes. As far as I can tell it _does_ do a fresh callout every time.


AIUI, exim sees no need to remember that the previous attempt gave a
temporary failure. It just does a fresh callout.

> > Usually, a solution to this kind of requirement would be a little
> > Perl script - invoked via ${run...} if you haven't got the Perl
> > scripting interface in your exim build.
>
> I could indeed do it with an external database, but that seems a little
> strange since Exim already does almost every part of what's required;


You'd be making use of exim's callout mechanism anyway; but AFAICS
you're going to have to keep a tally on the results for yourself.

> logging the results of callouts into a database, with timestamps etc.


Take a look in that data base, then, with something like (in our
case):

/usr/sbin/exim_dumpdb /var/exim/spool callout | more

You'll see that the cached results of callout are either 'accept' or
'reject' - never 'temporary fail'. Unless someone's looked into the
code and knows something that isn't shown here, I don't think you will
find the specific data that you need for running your plan. Sorry...

BTW, don't entirely forget that a bona fide sender _could_ be out of
contact for several days in adverse situations.