AW: Re: AW: Re: Message contains NUL characters - howto dump?

[Klemens Puritscher]

Markus Rebensburg schrieb:
> Klemens Puritscher schrieb:
> > Phil Brutsche schrieb:
> >   
> >> The error message is being created by the LMTP service - NUL 
> characters
> >> aren't valid in ASCII messages. The email in question is being 
> generated
> >> incorrectly somewhere, somehow.
> >>     
> >
> > thanks for your reply.
> > I know that in the email must be a NUL character, but I cannot see 
> this NUL character during a tcpdump.
> >
> > Do you know, or someone else in this list, who can I safe find this 
> NUL character?
> >
> >   
> Maybe it is a problem of lines ine the email which are longer than the
> standard allows. Cyrus has a fixed buffer for each line in the email. If
> the line is longer than this buffer lmtp inserts a terminating string
> character (NUL) itself. This could be the reason you cannot see the
> Character in the tcp stream of your mail.
> We have the same problem with the NUL character here produced by replies
> to emails with some HTML Attachments which have only one linebreak in
> the whole file.


thanks for this hint.
This possibility should I have already fixed, in my exim-config:

[...]
acl_check_data:
  deny   message      = Line too long
         regex        = ^.{4000,}
  accept
[...]

(IMHO is the max. line lenght in emails 4000 characters.)

Are there other possibilities for the lmtp error "Message contains NUL characters"?

regards,
Klemens



> Regards,
>      Markus
> >> What you need to do is either have the MTA reject the message during 
> the
> >> DATA portion of the SMTP transaction, or have the MTA remove the NUL
> >> characters before it passes the message on to the LMTP service.
> >>     
> >
> > Yes, this will be the next step.
> >
> >   
> >> Your email headers indicate you are using Postfix as your MTA, and I 
> am
> >> not familiar enough with that to tell you how to do what is necessary.
> 
> >>     
> >
> > Yes, that's right for outgoing emails.
> > The MTA for incoming emails (mx host) is exim.
> >
> > regards,
> > Klemens
> >
> >
> >   
> >> Klemens Puritscher wrote:
> >>     
> >>> Hello,
> >>>
> >>> I have a problem with one of our customers.
> >>> When he forwards an email with the thunderbird email client (windows
> >>> version), the lmtp-daemon on my cyrus-imapd (v2.3.13) rejects those
> >>> emails with the error "554 5.6.0 Message contains NUL characters".
> >>> ...ok, that's clear, there are "NUL" characters in the email.
> >>>
> >>> But I would show my customer, where the "NUL" character is.
> >>>
> >>> For tests, I generate a testmail, with "echo -e
> >>> "From:<sender at example.com>\nTo:<recipient at example.com>\nSubject:
> >>> test\n\ntest\0000test\n.\n" > mail_with_NUL.txt
> >>>
> >>> Now I dump the lmtp-session on the cyrus-imapd host with:
> >>> tcpdump -vv -XX -s 65535 -n -i eth1 "port lmtp
> >>>
> >>> and I see the "NUL" character:
> >>> ...
> >>>         0x0230:  7065 6564 2e61 740d 0a0d 0a74 6573 7400  peed.at....
> 
> >>>       
> >> test.
> >>     
> >>>         0x0240:  7465 7374 0d0a 2e0d 0a                   test.....
> >>> ...
> >>> 65 = e
> >>> 73 = s
> >>> 74 = t
> >>> 00 = NUL
> >>>
> >>> ...ok, fine, I can find the "NUL" character.
> >>>
> >>> But when I dump the lmtp-session with the customer email (which 
> get's
> >>> the error "554 5.6.0 Message contains NUL characters"), I cannot 
> find
> >>> this "NUL" character.
> >>>
> >>> Can someone tell me, what I did wrong?
> >>>
> >>> Thanks in advance.
> >>>
> >>> Klemens
> >>>
> >>> ----
> >>> Cyrus Home Page: http://cyrusimap.web.cmu.edu/
> >>> Cyrus Wiki/FAQ: http://cyrusimap.web.cmu.edu/twiki
> >>> List Archives/Info: http://asg.web.cmu.edu/cyrus/mailing-list.html
> >>>       
> >> -- 
> >>
> >> Phil Brutsche
> >> phil at optimumdata.com
> >>     
> >
> > ----
> > Cyrus Home Page: http://cyrusimap.web.cmu.edu/
> > Cyrus Wiki/FAQ: http://cyrusimap.web.cmu.edu/twiki
> > List Archives/Info: http://asg.web.cmu.edu/cyrus/mailing-list.html
> >
> >   
>