On 2025-01-25 at 15:53:28 UTC-0500 (25 Jan 2025 15:53:28 -0500)
John Levine via mailop <[email protected]>
is rumored to have said:
It appears that Bill Cole via mailop
<[email protected]> said:
On 2025-01-25 at 13:36:52 UTC-0500 (Sat, 25 Jan 2025 19:36:52 +0100)
Carsten Schiefner via mailop <[email protected]>
is rumored to have said:
Dear all -
my understanding of section 2.3. "Body" of RFC 5322 "Internet
Message Format"
(https://datatracker.ietf.org/doc/html/rfc5322#section-2.3)
is that a sole 0x0a as the body is sufficient and fully RFC
compliant: is this correct?
Yes.
Sorry, no, the CR (0x0d) in front of the LF (0x0a) is mandatory. But
you don't need anything after that.
Pedantry: Dovecot stores linebreaks as LF-only, as does Apple Mail and
every other MUA I've seen on any modern Apple OS.
My assumption was that Carsten was referring to stored mail which one
might examine easily before sending or after receiving, not IMAP wire
traffic which requires at least a sniffer and (outside of a lab) access
to server TLS keys. Actual bare LFs in SMTP, LMTP, and IMAP wire traffic
break MUAs and MTAs in ways that I'd expect that to be noisier than the
failure described.
So one should read my answer assuming that I read his references to 0x0a
as meaning logical linebreaks, to avoid writing a lecture on the
subtleties of linebreaks in moving email vs stored text.
Reason why I am asking is that have come across a strange behaviour
of the iOS 16.7.10 Mail App: an email with an empty body - i.e. with
just a sole 0x0a - will briefly pop up in the overview and then
quickly disappears again. If it shows up at all...
If it really just has an LF rather than CR LF that suggests your IMAP
server is misconfigured.
Right, but that's not the problem.
One can send a headers-only message, which should end in a blank line
(CRLFCRLF on the wire, LFLF on disk) but I don't think any MTA or
Dovecot will object if it is missing the terminal linebreak. I would not
be shocked if a MUA that has to present a message chokes on one without
that second linebreak, because that is pathological. It is a bit more
troubling if iOS mail is choking on a message consisting of a properly
terminated header block and a null body.
--
Bill Cole
[email protected] or [email protected]
(AKA @[email protected] and many *@billmail.scconsult.com
addresses)
Not Currently Available For Hire
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