| Hi Mikhail
This is one of those weird inconsistencies between IMAP and SMTP protocols … as far as I remember, the NUL character restriction only applies to the IMAP protocol … so your MTA (e.g. sendmail) is not breaking the SMTP RFC by transferring them. In my Exim configuration I have some code which strips the NUL characters from externally received messages and prohibits my local users from submitting messages which contain them - you could probably come-up with a similar thing for sendmail. This may be useful: http://info-cyrus.andrew.cmu.narkive.com/Rro4Nn9M/554-message-contains-nul-characters
Merlin
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Merlin Hartley
Computer Officer MRC Mitochondrial Biology Unit Cambridge, CB2 0XY United Kingdom
On 24.07.2017 10:41, Merlin Hartley
wrote:
NUL
characters are not permitted in e-mails …
As the RFC for IMAP states:
(3) The ASCII NUL character, %x00, MUST
NOT be used at any time.
But the message did go through sendmail...
Ken Murchison wrote:
What is the Content-Transfer-Encoding of the
email? Was the message Base64 encoded, or is the PNG included as
raw binary data?
Raw... Here are the full headers (the first line -- the From_ -- is
removed by sed before feeding the rest into deliver):
From mi@xxxxxxxxxxx Mon Jul 24 00:53:00 2017
Received: from narawntapu.narawntapu (localhost [127.0.0.1])
by narawntapu.narawntapu (8.15.2/8.15.2) with
ESMTPS id v6O4r05T003160
(version=TLSv1.2
cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO)
for <mi@narawntapu.narawntapu>;
Mon, 24 Jul 2017 00:53:00 -0400 (EDT)
(envelope-from mi@narawntapu.narawntapu)
Received: (from mi@localhost)
by narawntapu.narawntapu (8.15.2/8.15.2/Submit)
id v6O4r0c9003159;
Mon, 24 Jul 2017 00:53:00 -0400 (EDT)
(envelope-from mi)
Date: Mon, 24 Jul 2017 00:53:00 -0400 (EDT)
Message-Id: <201707240453.v6O4r0c9003159@narawntapu.narawntapu>
From: Cron Daemon <mi@xxxxxxxxxxx>
To: mi@narawntapu.narawntapu
Mime-Version: 1.0
Content-Type: image/png; charset=binary
Content-Transfer-Encoding: 8bit
Subject: Cron <mi@narawntapu> cat foo.png
Should sendmail have re-encoded with something other than 8bit? I
don't like doing that, because it increases the filesizes to no
obvious benefit... Thanks!
-mi
|
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