Re: RMAIL, MIME-related bug

[Kevin Rodgers]

Juri Linkov wrote:

> Kevin Rodgers <address@hidden> writes:
> > I did a little work on this issue about 2 1/2 years ago.  My approach
> > was to define a bookmark as a URL whose protocol is "mailmessage", so
> > that I could use Emacs' url.el library to parse it and ange-ftp.el to
> > access remote //address@hidden folders.  However, I wrote it as an add-on
> > to VM, so the code that actually views the folder and selects the
> > message would have to be converted to Rmail.  And it would have to be
> > extended to handle IMAP folders (cf. file folders).
>
> Using URL for references to messages is a good solution, but instead
> of inventing ad hoc protocol name, it's better to use standard name
> "mid" defined by http://www.ietf.org/rfc/rfc2392.txt.


Thanks for the pointer, but I find that document somewhat disappointing.

For one thing, I was confused by this:

        A "cid" URL is converted to the corresponding Content-ID message
        header [MIME] by removing the "cid:" prefix, converting the % encoded
        character to their equivalent US-ASCII characters, and enclosing the
        remaining parts with an angle bracket pair, "<" and ">".  For example,
        "cid:foo4%25foo1@bar.net" corresponds to

            Content-ID: <address@hidden>

        Reversing the process and converting URL special characters to their
        % encodings produces the original cid.

        A "mid" URL is converted to a Message-ID or Message-ID/Content-ID
        pair in a similar fashion.

Shouldn't "%25" have been converted to "%":

        Content-ID: <address@hidden>

But more importantly, the mid and cid URLs do not actually specify a
LOCATION: that makes them more like a URN than a URL.


> Then, for example, opening the link <mid:address@hidden>
> should start a mail reader, find corresponding message by its
> Message-ID, prepare article buffer and switch to it (e.g. in case of
> Gnus to call the function `gnus-summary-goto-article'; other mail
> readers should have a similar function).


Shouldn't the cid and mid schemes specify a location via the Common
Internet Scheme Syntax defined in RFC 1738?  That way, you could specify
a folder file, or a POP or IMAP server (and user and password).


> I'm not sure yet, where this could be implemented: url.el is not part
> of Emacs (BTW: Why?); thingatpt.el mentions this protocol name, but
> that's all; perhaps this should be done partially in ffap.el.

As long as it respects the read-mail-command variable.  To do that
correctly, I think we would need to define an interface like compose-mail
that would accept all the arguments that might be necessary to specify a
message (folder file and format; or server, protocol, user, and password;
plus message id); then a new utility define-read-mail-command (analogous to
define-mail-user-agent) that would associate each read-mail-command to a
function that supports that interface.


Otherwise, how would Emacs know where to search for the Message-Id?

--
Kevin Rodgers