bug#6574: 24.0.50; Rmail 23 uses a broken mailbox format (mboxo) instead of a sane one like mboxrd

bug#6574: 24.0.50; Rmail 23 uses a broken mailbox format (mboxo) instead of a sane one like mboxrd

[Mark Lillibridge]

    There is a family of incompatible mbox formats for storing mail; see
http://homepage.ntlworld.com./jonathan.deboynepollard/FGA/mail-mbox-formats.html
for all the details.

    Examining unrmail.el from Gnu emacs 24.0.50.1 (lines 228-231):

	    ;; ``Quote'' "\nFrom " as "\n>From "
	    ;;  (note that this isn't really quoting, as there is no requirement
	    ;;   that "\n[>]+From " be quoted in the same transparent way.)

clearly shows that Rmail 23 is using the mboxo format.  

    Unfortunately, this is known to be a bad format because it
irreversibly alters messages.  I strongly recommend switching to a
format like mboxrd, which does not have this problem.

(In particular, any line in a message body starting with "From " is
changed to ">From " in a nonreversible manner; this will screw up MIME
attachments, among other things, with nonzero probability.)

- Mark
PS, the documentation needs to explain which mbox format is used, rather
than saying "the standard mbox format", of which there is no such thing.

bug#6574: 24.0.50; Rmail 23 uses a broken mailbox format (mboxo) instead of a sane one like mboxrd

[Glenn Morris]

Version: 24.4

Mark Lillibridge wrote:

>     Examining unrmail.el from Gnu emacs 24.0.50.1 (lines 228-231):
>
> 	    ;; ``Quote'' "\nFrom " as "\n>From "
> 	    ;;  (note that this isn't really quoting, as there is no requirement
> 	    ;;   that "\n[>]+From " be quoted in the same transparent way.)
>
> clearly shows that Rmail 23 is using the mboxo format.  

Unrmail has used mboxo when converting from Babyl to mbox since forever;
it's not something new that appeared in 23. I think the lack of comments
over the years indicates this is not a big deal.

However, I agree that mboxrd is better so I made unrmail default to
that, with an option unrmail-mbox-format that you can set to mboxo or
mboxrd.

Rmail itself (as opposed to unrmail) does not care about mboxo or
mboxrd, with the exception of the display of non-MIME messages.
I added a similar option rmail-mbox-format for that.

(http://debbugs.gnu.org/9841 remains as a separate issue at this time)