[Exim] rejecting after DATA and hotmail, ah ah.

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Autor: Giuliano Gavazzi
Datum:  
To: exim-users
Betreff: [Exim] rejecting after DATA and hotmail, ah ah.
Dear all,

I wonder if this funny side-effect of rejection after DATA with
hotmail is known. It might be of interest to those using a data acl.

I have implemented a "too many bad recipients" condition that kicks
in when at least 2 bad recipients are rejected (for any reason). It
drops the connection when it is triggered during the RCPT phase
(otherwise the sender might keep on trying other addresses) while it
just sends a 5XX code when triggered at the DATA phase (this is
necessary as the $rcpt_fail_count might increase after the last rcpt).

I have done a test from an hotmail account and while the RCPT acl
gives a normal notification failure, the DATA acl will cause
extraneous data to be included as you can see from the following
(usernames have been obscured):

(I have also tested this with a simple blacklisting of the sender at
the data phase, it still gives garbage but does not so far include
the extraneous RCPT negotiations)
From :
postmaster@???
To :
xxxxxxxxxxxxx@???
Subject :
Delivery Status Notification (Failure)
Date :
Fri, 3 Jan 2003 16:03:02 -0800
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This is an automatically generated Delivery Status Notification.

Delivery to the following recipients failed.

       notexist1@???
       anexistinguser@???
       notexist2@???






Reporting-MTA: dns;hotmail.com
Received-From-MTA: dns;mail.hotmail.com
Arrival-Date: Fri, 3 Jan 2003 16:02:45 -0800

Final-Recipient: rfc822;notexist1@???
Action: failed
Status: 5.0.0
Diagnostic-Code: smtp;550 unknown user


Final-Recipient: rfc822; anexistinguser@???
Action: failed
Status: 5.0.0
Diagnostic-Code: smtp;550 Too many bad recipients 2 out of 3
line by itself
.138]
250-SIZE 5242880
250-PIPELINING
250-AUTH LOGIN PLAIN
250-STARTTLS
250 HELP
0 HELP

-XADR
250-XSTA
250-ETRN
250-XGEN
250-RELAY
250 SIZE 0
I NTLM LOGIN
250-X-EXPS=LOGIN
250-AUTH GSSAPI NTLM LOGIN
250-AUTH=LOGIN
250-X-LINK2STATE
250-XEXCH50
250 OK

cipient ok
(COMMENT: I have removed the usernames from the following lines:
hanmail.net has nothing to do with me, and this looked like a
combinatorial scan)
550 5.1.1 <@hanmail.net>... No such user
.5 <@hanmail.net>... Recipient ok
250 2.1.5 <@hanmail.net>... Recipient ok
550 5.1.1 <@hanmail.net>... No such user
250 2.1.5 <@hanmail.net>... Recipient ok
250 2.1.5 <@hanmail.net>... Recipient ok
250 2.1.5 <@hanmail.net>... Recipient ok
550 5.1.1 <@hanmail.net>... No such user
250 2.1.5 <@hanmail.net>... Recipient ok
250 2.1.5 <@hanmail.net>... Recipient ok
250 2.1.5 <@hanmail.net>... Recipient ok
250 2.1.5 <@hanmail.net>... Recipient ok
250 2.1.5 <@hanmail.net>... Recipient ok
550 5.1.1 <@hanmail.net>... No such user
250 2.1.5 <@hanmai

Final-Recipient: rfc822;notexist2@???
Action: failed
Status: 5.0.0
Diagnostic-Code: smtp;550 unknown user


From :
"" <xxxxxxxxx@???>
To :
notexist1@???, anexistinguser@???, notexist2@???
Subject :
test reject at DATA: 2 inexistent 1 existent
Date :
Sat, 04 Jan 2003 00:02:45 +0000