On 07Jun2019 23:22, Kurt Hackenberg <k...@panix.com> wrote:
On 2019-06-07 07:22, Cameron Simpson wrote:
If fetchmail's delivering to a programme, nothing prevents that being
an arbitrary script to premangle a leading From_ line. Hmm. I've got
a script in my bin directory called "unfrom_" for exactly this
purpose, which reads:
#!/usr/bin/env sed -f
#
# Transmute leading "From " line on email message, if any.
# - Cameron Simpson <c...@cskk.id.au> 13jul2002
#
1{s/^From /From_: /}
You can just include that script in a pipeline ahead of maildrop.
Yep.
I've also seen From_ lines in maildir message files, and on the stdin
of delivery agents. Both are wrong, in my opinion. I think mbox From_
lines should not exist anywhere outside mbox files.
Well, the From_ isn't just a delimiter for mbox lines, it also
historically contains the envelope address from the mail system - the
address used for this delivery (versus whatever may be in the headers).
So it has some useful forensic information.
I've written a script much like yours, to drop the damn From_ line
from an incoming message passed to a delivery agent. I think your
script does something that's not quite right: it transforms the mbox
From_ line to something that's not RFC 822. You could do, say,
s/^From /X-Mbox-From: /
I'm digging through RFC 8522:
https://tools.ietf.org/rfcmarkup/5322
which is the modern incarnation of RFC822, but it doesn't seem very
prohibitive on header field names. Section 2.2 says:
Header fields are lines beginning with a field name, followed by a
colon (":"), followed by a field body, and terminated by CRLF. A
field name MUST be composed of printable US-ASCII characters (i.e.,
characters that have values between 33 and 126, inclusive), except
colon.
This is confirmed in section 3.6.8:
optional-field = field-name ":" unstructured CRLF
field-name = 1*ftext
ftext = %d33-57 / ; Printable US-ASCII
%d59-126 ; characters not including
; ":".
So I think "_" is permitted :-)
Or -- my recommendation -- just drop it. (Of course, drop it only if
that first line really is an mbox From_ line.)
I'm a hoarder and dislike discarding anything.
Cheers,
Cameron Simpson <c...@cskk.id.au>
