Re: [Exim] exim3 RBLs and temporary error

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Autor: Alan J. Flavell
Data:  
Para: James P. Roberts
CC: Exim users list
Asunto: Re: [Exim] exim3 RBLs and temporary error
On Sun, 10 Nov 2002, James P. Roberts wrote:

> I don't know about Exim 3, but in Exim 4 you could use something like
> this in an ACL:
>
>  deny    message = host in DNS blocking list or DNS data not available
>           dnslists = +defer_unknown:relays.ordb.org:relays.osirusoft.com


Which particular ACL were you doing this in?

> By the way, if any experts out there have opinions on why I might be
> doing this wrong, or could be doing it better, please let me know so I
> can fix it. I did have one person call to complain their email to me
> bounced with that message, even though they are not in the RBLs,


Nevertheless, you _were_ looking them up, so the lookup could have
timed-out, irrespective of whether they were in fact listed or not.

> implies a DNS timeout for that particular email, right?


What this is doing is looking up the RBLs for the calling IP, not the
"email", just to be sure we understand each other...

> My intent was not to bounce the mail, but to do a temporary reject,


That is indeed what's supposed to happen, if you have +defer_unknown
to the left of the relevant RBL.

> to permit the sending MTA to retry,


It ought to do that. However, some MTAs seem to react in unexpected
ways to error codes, depending on which ACL phase you're sending them
at. The most irritating for me are those which react to a DATA ACL
5xx as if it was a retryable error.

It sounds as if you think you've found one (other than spamware, where
this would be a commendable behaviour ;-) which treats a 4xx as fatal.

> Any thoughts?


You are doing what the documentation says you should do!