Re: sendmail corrupts long header From

Mon, 14 Sep 2009 22:48:57 -0700, vova did cat :

Is this bug in sendmail?

If not a bug in sending tools and/or your description of the said
header, it's probably just a question of choice, safe choice in
sendmail and bad choices in sending client implementation of about when
a header size becomes ludicrous.

Unfortunately, my users don't account such header ludicrous)

they could be stateful for internal mail but they
certainly are a bit b(uf|ea)fy for outter space ;-)

I suppose that checking RFC5321 at sections 4.5.3.1.{1,2,4} could be a
start?

My example doesn't violate any of these sections. It is header From with
4 strings of 75 (about) chars in length.

well? 4*(64+N) used to be bigger than 256.


Maybe this can be applied:
4.5.3.1.3. Path
The maximum total length of a reverse-path or forward-path is 256
octets (including the punctuation and element separators).

Do you mean that the huge unreadable lines you quoted are not
only unreasonable headers but real SMTP <path>s ???



Strange thing is that sendmail behave differently for different header's
length.
Original header:

From: <text> <user@domain>

If it's "very long", sendmail convert it to From: <user@domain>
(i.e. just drops <text>)

If it's "just long", then
From: <text> <corrupted address>
(i.e. drops chars from the end)

Does anyone know limits and algorithm of processing for long headers in
sendmail?

there are better people than me here that will help you on that side :-)

Now, mind that on each relay your mails will pass through you may
find their mailmasters enforced some header size settings,
see in the cf/README about confMAX_MIME_HEADER_LENGTH
(eg grep -C3 confMAX_MIME_HEADER_LENGTH /usr/share/sendmail-cf/README)
My usual settings are 256/128 and I think you'll meet this setting
on many other relays than mine.
.

Relevant Pages

  • Re: 127.0.0.1 in Received:From header
    ... I'm seeing the following header on messages send from my server: ... Which is the non-root submit mode of sendmail connecting back to port ... 25 on the local host to submit the message, ...
    (comp.mail.sendmail)
  • Sendmail Config. question
    ... is about a month behind on patch levels (sendmail patch up-to-date). ... a problem removing the hostname from the 'FROM:' header of any email sent from ... Since I don't have DNS resolving this host (internal host, ...
    (SunManagers)
  • RE: configuring sendmail to reject spoofed email addresses
    ... exactly as Steve has (assuming SendMail is capable of this). ... Donald Tyler wrote: ... sendmail to test against the "Return-Path" header. ... I have postfix configured to reject anyone claiming to be from mydomain.com ...
    (RedHat)
  • RE: configuring sendmail to reject spoofed email addresses
    ... Donald Tyler wrote: ... First, I no longer use sendmail as my MTA, so I can't answer your question ... sendmail to test against the "Return-Path" header. ... I have postfix configured to reject anyone claiming to be from mydomain.com ...
    (RedHat)
  • Re: masquerading envelope not working in mutt
    ... > from my side since I have sendmail set for SMART RELAY through my ISP. ... To see your private IP address in the header is quite normal. ... There is no bounce reason! ... > tagged onto the envelope sender. ...
    (Fedora)