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 -- Merlin Hartley Computer Officer MRC Mitochondrial Biology Unit Cambridge, CB2 0XY United Kingdom > On 24 Jul 2017, at 17:14, Mikhail T. <mi+cy...@aldan.algebra.com> wrote: > > On 24.07.2017 10:41, Merlin Hartley wrote: >> NUL characters are not permitted in e-mails … >> https://helpdesk.pscs.co.uk/690163-Data-stream-contained-NUL-character >> <https://helpdesk.pscs.co.uk/690163-Data-stream-contained-NUL-character> >> >> As the RFC for IMAP states: >> https://tools.ietf.org/html/rfc3501#section-9 >> <https://tools.ietf.org/html/rfc3501#section-9> >> (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 m...@example.com <mailto:m...@example.com> 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> <mailto:mi@narawntapu.narawntapu>; > Mon, 24 Jul 2017 00:53:00 -0400 (EDT) > (envelope-from mi@narawntapu.narawntapu > <mailto: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> > <mailto:201707240453.v6O4r0c9003159@narawntapu.narawntapu> > From: Cron Daemon <m...@example.com> <mailto:m...@example.com> > To: mi@narawntapu.narawntapu <mailto: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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