Re: [Exim] Lousy error message when verify = header_sender f…

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Autor: Philip Hazel
Data:  
A: Greg Ward
CC: exim-users
Assumpte: Re: [Exim] Lousy error message when verify = header_sender fails
On Thu, 5 Sep 2002, Greg Ward wrote:

> Here's a snippet of my ACL config from such a server:
>
>   acl_smtp_data = check_message
>   [...]
>   check_message:
>     [...]
>     deny    !senders = :
>             !verify  = header_sender
>             message  = no valid sender address in any header line


That's wrong. What you want is

     deny    !senders = :
             message  = no valid sender address in any header line
             !verify  = header_sender


(or stick "message" first) because a "message" item applies to failures
that happen after it has been processed. If you put it last, it won't
have been seen before the denial happens.

> >>> dnslookup router: defer for spammer@???
> >>> message: host lookup did not complete
> >>> deny: condition test deferred
> 451 Temporary local problem - please try later


That bland wording is the default for temporary failures.

> It took me several minutes of poking around to determine just what the
> "temporary local problem" is -- and in fact, it's not a local problem at
> all!


Well, it depends on what you mean by "local". :-) It's local in the
sense that your local host can't complete routing of the address. If I
went in for anthropomorphic error messages, I might have chosen "I have
a problem in checking this address. It seems to be something that might
get fixed, so I'm giving you a temporary error code."

> Here's how Exim explains this DNS problem:
>
> $ exim -bt spammer@???
> spammer@??? cannot be resolved at this time:
> host lookup did not complete


Typical DNS timeout problem. The servers for the domain are presumably
unreachable for some reason. Not uncommon.

--
Philip Hazel            University of Cambridge Computing Service,
ph10@???      Cambridge, England. Phone: +44 1223 334714.