Re: Timezone in mbox separator (From) line

On 2020-10-06 20:00, Ken Olum wrote:

> I'm using exim and have done nothing special to configure exim's
> timezone handling.  When it delivers to a mbox-format file, it writes
> the separator line at the the beginning of the message with the
> local time and no timezone.  This seems to be wrong.  According to
> RFC4155's specification of the "default" mbox format, this should be in
> UTC (with no timezone marker).  Indeed squirrelmail using imap reports
> this time incorrectly.
> 
> So I guess I should get exim to use UTC for that line, except that the
> mailutils "mail" program uses the time from there unaltered.  If imap
> thinks that this line is in UTC, shouldn't mail think that also and
> convert it to local time before displaying it?


RFC 4155 is not definitive. In fact, as far as I know, that variant of 
mbox has never been implemented.

Note that RFC 4155 doesn't define a file format. It defines a MIME type, 
a way to encode data on the network, that is similar to a file format 
that's common on Unix systems. The IETF is only about the internet. The 
IETF considers how received mail is stored, or even whether it's stored, 
to be a local matter, outside the purview of the IETF.

Mbox is not really standardized. It has become a de facto standard -- 
well, several de facto standards. It has four or five major variants, 
and many lesser variants, all partially incompatible.

Here's what Wikipedia says about mbox:
<https://en.wikipedia.org/wiki/Mbox>

 From looking at mail I've received into mbox files, the time in the 
From_ line seems to be mostly local time, though sometimes it's UTC. If 
I remember, I saw 80-90% local time. The most common syntax for that 
time is the same as what's produced by the C library function ctime(); 
that function produces local time.

I'm surprised that squirrelmail even looks at the time in the mbox From_ 
line. I'd expect it to use the time in the message's Date: header.