> This is, in my opinion, a real weakness of UW-IMAP. The "Maildir" folder, as
> used by Dovecot for example, avoids that issue altogether.

It has nothing to do with maildir, and everything to do with being able to
insist that only certain classes of objects located in certain locations in the
filesystem are accessible via IMAP.

When UW IMAP was first written, nearly 20 years ago, that was not an
acceptable position.  People would refuse to use IMAP at all if they had to
adjust their way of doing things to comply with "IMAP requirements."
Back then, mail was in traditional UNIX (mbox) format and could be
anywhere (and I do mean anywhere) in the user's home directory tree,
limited only by the user's imagination.

To make matters worse, even hiding dot files was unacceptable.  How
dare I hide something that is on the server; that's up for the IMAP
client to decide & etc.  The only reason why the hide dot file option
exists at all is because I snuck it in because I felt that it was the right
thing.

So, now we're stuck with not knowing, nor of being able to restrict,
where the mail data lives.  What about the data type?

Plus, UW IMAP supports 8 or so formats of local mailbox.  Any one of
these may be in use.  Some users use more than format.  So, for
every object encountered in the filesystem, it might be any of these
8 and the only way to determine is to look.

Guess how slow it was to look on the filesystems of the early 1990s.
Hence the use of the dummy driver, whose main purpose is to
consider ALL filesystem objects as being part of the mail store.  It
was the only way to allow listing mailboxes to complete before the
sun novas.

Remember as well that UW IMAP can export any arbitrary text file.
There was this idea (not mine) of using IMAP as a replacement for
FTP to fetch files from a repository.  That wasn't actually a bad idea;
HTTP is used for that purpose commonly today.  But it didn't take off.

Dovecot does not labor under the same set of design restrictions.  The
world is a much easier place when you can decide that all mail must
either be maildir -- which is easily identifiable by inspecting a directory
without reading file data -- or mbox files in a well known place.

If UW IMAP went to that much easier place in the early 1990s, we
would not be having this discussion now.  UW IMAP would have failed
to gain acceptance, the CMU folks wouldn't have joined the IMAP
effort, and the IMAP protocol would have languished in obscurity as
some crazy idea that Mark Crispin had decades ago that never took
off.  IMAP would have had good company -- there were lots of really
good protocol ideas that ended up in the refuse heap of history for
being at the wrong place at the wrong time.

Moving forward...

I have given serious consideration to deleting support for some of the
old formats in Panda IMAP, and perhaps even requiring that mix be
the one and only format.  That would, in effect, make Panda IMAP
behave just like Dovecot in that regard.  People could always use UW
IMAP (at least until it software rots) if they want to use one of the
old crufty formats.

-- Mark --

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