Re: [exim] Strange Sender Verification behaviour

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Author: Renaud Allard
Date:  
To: Philip Hazel, exim-users
CC: exim-users
Subject: Re: [exim] Strange Sender Verification behaviour
Indeed, it is definitely not an exim bug. I examined the logs to find
other servers where I get this kind of behaviour, and they all appear to
run alligate mail server.

On 2/13/2006, "Philip Hazel" <ph10@???> wrote:

>On Mon, 13 Feb 2006, Renaud Allard wrote:
>
>> Here is the result of the test. The callout was cached, so I suppressed
>> the cache before sending the message. I also removed greylisting because
>> it would have been unpractical for debugging.
>>
>> I included the full file just in case.
>
>Thanks for the test. It shows something very weird. These are the
>important lines. This is the SMTP conversation during the callout check:
>
> SMTP<< 220 digest2.cali.co.uk ESMTP server ready (Alligate v1.5.11.16-13.2-0.2)
> SMTP>> HELO mail.llorien.org
> SMTP<< 250 digest2.cali.co.uk
> SMTP>> MAIL FROM:<>
> SMTP<< 250 OK
> SMTP>> RCPT TO:<mail.llorien.org-1139826047-testing@???>
> SMTP<< 550 5.1.1 <mail.llorien.org-1139826047-testing@???> is not a valid mailbox
> SMTP>> RSET
> SMTP<< 250 OK
> SMTP>> MAIL FROM:<>
> SMTP<< 550 5.1.1 <mail.llorien.org-1139826047-testing@???> is not a valid mailbox
> SMTP>> QUIT
>
>Notice what happens: the first test is correctly rejected at the RCPT TO
>stage. Exim then sends RSET and MAIL FROM:<> again. This time, the
>remote host gives the response that Exim logs! So as far as I can
>see, the remote host is behaving weirdly. (And the remote host is not
>Exim.)
>
>Why is Exim sending the RSET? Look at the form of the RCPT TO address.
>That is the form used for testing "random" local parts. So I presume you
>have specified verify=sender/random in your ACL. Since the "random"
>local part is rejected, Exim proceeds to try to verify the actual
>sender, but it never gets that far because of the bad behaviour of the
>server.
>
>I do not believe this is an Exim problem. The obvious workaround is to
>remove the "random" test, at least for this domain.
>
>I tried testing this by hand, and it is quite consistent:
>
>$ telnet calligate2.cali.co.uk 25
>Trying 62.172.47.141...
>Connected to calligate2.cali.co.uk.
>Escape character is '^]'.
>220 digest2.cali.co.uk ESMTP server ready (Alligate v1.5.11.16-37.3-0.6)
>ehlo test.domain
>250-digest2.cali.co.uk
>250-AUTH LOGIN
>250 SIZE
>mail from:<>
>250 OK
>rcpt to:<testunknownuser@???>
>550 5.1.1 <testunknownuser@???> is not a valid mailbox
>rset
>250 OK
>mail from:<>
>550 5.1.1 <testunknownuser@???> is not a valid mailbox
>
>So it is definitely broken.
>
>Philip
>
>--
>Philip Hazel            University of Cambridge Computing Service
>Get the Exim 4 book:    http://www.uit.co.uk/exim-boo