Re: Add Maildir support to RMAIL

[Tim Cross <theophilusx@gmail.com>]

csh <csh@bluehome.net> writes:

> Eli Zaretskii <eliz@gnu.org> wrote ..
>> > From: csh <csh@bluehome.net>
>> > Cc: ane@iki.fi, emacs-devel@gnu.org
>> > Date: Sun, 25 Jul 2021 07:18:23 -0700 (PDT)
>> > 
>> > Eli Zaretskii <eliz@gnu.org> wrote ..
>> > >   $ movemail --version
>> > 
>> > bash: movemail: command not found...
>> 
>> Then I guess you should install GNU Mailutils.
>
> I asked you what the package name was.  I told you that I cannot find it. 
>
> [liveuser@localhost-live ~]$ dnf search mailutils
> Last metadata expiration check: 1:44:35 ago on Sun 25 Jul 2021 09:07:46 AM EDT.
> No matches found.
> [liveuser@localhost-live ~]$ 
>
>> Btw, I'm not sure I understand completely what kind of Maildir support
>> do you need and why.  Your original message said:
>> 
>> > I really love the simplicity of reading mail with RMAIL, but most email providers
>> no longer use the mbox format for mail.
>
> My mail is in Maildir format.  It is not in mbox format.
>
>> What do you mean by "email providers", and how do you use that to get
>> your email before reading it in Emacs?
>
> I use bluehome.net, which stores mail in Maildir format, but I am sure Google uses 
> Maildir format for its inboxes, too.
>
> Right now, I am using the webmail Webmin interface.  Sometimes I use Evolution.  Other
> times I use Thunderbird.  I just used OfflineIMAP to fetch all my mail into ~/Mail/ on
> my local machine.

I think you have some conceptual confusion regarding how all of this
works.

How your email provider (e.g. google) stores messages is irrelevant. You
retrieve messages from your provider via imap (or possibly pop3), which
is a protocol that sits at a higher level than storage - it does not
know or care about how the messages are stored. It simply retrieves the
message and passes it through to your imap client.

In your case, your imap client is OfflineIMAP, which I believe stores the
messages using maildir format. There are of course many other similar
programs (I use mbsync). There are also a number of other alternatives,
using things like procmail, local mail servers, local imap servers and
many other options.

All that really matters is that the messages are stored in a format that
your mail reading client can understand. It has been decades since I
used Rmail, but from memory, it used its own internal format for storing
messages - it use to be that rmail would read the messages from the
traditional mbox format on local system and move them into rmail's
preferred format. Other clients did similar - for example, VM. In the
past, I use to use fetchmail and procmail to retrieve messages via imap,
run them through procmail to filter and sort, write them to mbox files
which VM would then read in and store locally in VM's own format.

These days, I use mu4e and mbsync. My messages are stored in maildir
format and I have the power of 'mu' to search/manipulate them and the
ease of mu4e for reading. The nice thing about mu4e is that it uses
Emacs' standard message mode for composing messages and Gnus' for
displaying/rendering messages (but without the overhead/confusion of a
Gnus interface). Another 'simple' mail interface which is quite popular
is 'notmuch', which I've not used, but I believe is based on similar
principals i.e. small utilities which are combined together with a nice
interface wrapper written in Emacs lisp.

The only time when you really need to worry about what storage format
your email client uses is when it comes to sorting out backups or
perhaps fixing data corruption. The maildir architecture became popular
because mbox was seen as a bit inefficient and fragile (large files
where any corruption would make all messages unavailable) or when using
multiple clients.

I think it is a bad idea to try and share the same data across clients.
I've found that even when a client claims to use maildir format, there
can be some subtle differences in implementation which can affect how
reliable the storage is. These days, with cheap storage and fast
networks, I find it better to setup all clients to have their own local
store and just use imap to keep things synchronised. Now I can read
messages from numerous different clients on different platforms and
everything is 'in sync'.