(File this under "Reminders for the future Matt")
I use, and highly recommend,
OfflineIMAP for the
synchronisation of your e-mail between your daily working machine and your
IMAP server (if you don't have an IMAP server available for your mail, it's
high time you got one). You point it at an IMAP server somewhere far, far
away, and a local Maildir, and all of your mail and folders magically get
synchronised in both directions. New folder on the server? After the next
run, it'll be on your local machine. Even more magical, though, is that
any new mail or folders you create on your local machine will be uploaded
to the server. Woohoo! Offsite Backups!
(Before you GUI mail users say "pfft, my client does that all for me", I'll
remind you that I don't need to chew several hundred megs of core to delete
my spam)
I've got
some
magical procmail rules (specifically, look for "ARTFUL PROCMAIL") that
automatically filter list e-mail into individual folders (with automatic
creation of the folder if necessary, of course). This makes mailing lists
soooo much easier to handle. Of course, when I unsubscribe from the list a
couple of weeks later, that folder is still sitting there, empty and
forlorn.
I don't mind empty directories, except that they slow down the OfflineIMAP
sync run, since it asks "any new mail in here?" for every one of them. I'd
just delete them from my local machine periodically, except that
OfflineIMAP can't delete folders off the server if you remove them from
your local Maildir (and vice versa). Instead, the folder gets re-created
on the local machine, which is definitely not the result I'm looking for.
I'm pretty sure this is an IMAP limitation, so I'm not criticising John
Goerzen for not implementing this particular feature. However, the empty
folders bother me a bit, so I decided to do something about it. Namely, I
hacked up some little shell one-liners.
These one-liners are all dependant on you having the same IMAP server
(Courier) and folder name mapping (none) as me, otherwise there's a good
chance that your file names won't match the patterns I've used. For
reference, My folders on the server are dot-directories under
$HOME/Maildir, and my folders all start with
INBOX. on the
client. Also, both sides use periods to separate folder levels. As an
example, e-mail to the debian-devel-announce list gets stored in
$HOME/Maildir/.lists.debian-devel-announce on the server, and
$HOME/Maildir/INBOX.lists.debian-devel-announce on the client.
I've got one big before you start warning: this process involves
deleting things. If you're not able to verify that what these snippets are
doing is correct for your particular situation, then please do not run
them. Also, if running them causes all your e-mail to disappear or your
cat to fall pregnant (despite being spayed and/or male), then that isn't my
fault. The only warranty I give is that It Works For Me. It May Not Work
For You.
As a first step, make sure that your local and remote mail stores are in
sync -- presumably by running OfflineIMAP. Otherwise, a folder which is
empty on one side might not be quite-so-empty on the other side, and that
would possibly make for sadness. Stopping e-mail from coming into your
mailboxes would be good, too -- I just turned off my MTA for a few minutes,
because clogging other people's queues is fun. Doing something smart with
procmail would also work.
On the OfflineIMAP client machine (laptop, home desktop, whatever),
cd into your local mail store, and run this to generate a list of
IMAP folders that don't have anything in them:
for i in INBOX.*; do find $i -type f grep -q $i \
(echo $i sed 's/^INBOX//'); done >/tmp/empties
The contents of
/tmp/empties should look something like:
.Deleted
.junk
.lists.debian-devel-announce
.lists.something-funny
.spam
Review the list of folders it produced (just to make sure nothing
really unpleasant ended up in the list), and then run:
for i in $(cat /tmp/empties); do rm -rf INBOX$i; done
to delete all the empty folders.
Next, copy the list of folders onto the IMAP server (yes, you need
shell access on the server to do all of this; that's why I run a
Linode),
cd into your Maildir on
the server, and run this:
rm -rf $(cat /tmp/empties)
That removes the folders from the server as well.
For some reason, OfflineIMAP doesn't notice that a folder has gone away,
and so it doesn't remove the metadata for the deleted folders from it's
cache. I'm not sure if that hurts performance or is otherwise injurious to
your health. To be ultra-neat, go into
$HOME/.offlineimap (or
wherever your metadata dir is) on the client machine and run
for i in $(cat /tmp/empties); do find . -name INBOX$ i ; done xargs rm -rf
And that makes everything clean and tidy.
Now, of course, someone's going to point me to a small script that finds
all of your local empty folders and deletes them locally then issues an
IMAP "delete folder" command on the server. But I had fun working all this
out, so it's not a complete waste.
I couldn’t resist in giving him a grml-CD. Oh, and we were running out of grml-CDs earlier than expected. Thanks to my girlfriend - who can even explain the difference between grml meilenschwein and grml64 to you now 
- I had the chance to attend some few talks - besides 
but I just received a pointer to the 
Including a final synchronisation of all files to the new storage, about two hours it took uniconv to convert the file names and a aunch break, we were finished after about 14 hours of work. Until now it seems that our users didn t notice the change at all, except for those who realized that they have much more free space now. Looks like a successful weekend so far! 
