Maildir in Subversion

Ken Bloom kbloom at
Sun Aug 13 05:38:47 CEST 2006

On Saturday 12 August 2006 14:59, Joerg Lange wrote:
> Hi,
> I am wondering if it makes sense to store emails in a Maildir in a
> versioned repository.
> I had my personal data in a CVS repository for years now, last month
> I changed to SVN. I use Windows mostly, Linux only rarely. However, I
> have set up Courier IMAP on a server and I am thinking about moving
> my email archives from Outlook PST files to that IMAP account and
> have a cron job on the server do a "svn add" periodically.

Adding files to the mailbox isn't the only file operation that a mail 
client has to do to a Maildir. There are several others:
* various flags (including whether a message has been read) are stored 
in a filename, so the filename for a message *will* change.
See for more information about the 
* files get moved between directories (from new to cur) when the mail 
client sees them for the first time.
* you might delete mail.

It's going to be incrediby difficult or impossible to keep svn 
synchronized with the changes your mail client or IMAP server will make 
to the contents of the maildir.

(Btw, the third bullet point is also an argument against storing MH 
mailboxes in a version control system)

Arguably these are less problematic in your setup (which is just 
archiving) than in a setup with delivery and active reading, but why 
wouldn't you just use mbox format? Obviously you'll answer, "because 
that's all that courier supports." So I'll ask: is  Courier IMAP 
essential, or can you switch to a different IMAP server, such as 
dovecot which supports both mbox and maildir?

With mbox, you only need to deal with svn when you add/remove *folders* 
(not individual messages), which will be a lot less common, even on a 
setup with active delivery.

An interesting side point: in my setup, I don't version or synchronize 
my mail at all. Anything mail related is handled over SSH to my server. 
I back up using
$ mkisofs -root backup-$VERSION -old-root backup-$OLDVERSION
so mkisofs takes care of only backing up the files that have changed. 
(The ones that haven't changed it essentially hard-links in from 
elsewhere on the CD, although it's not exactly hard-linking because the 
two files don't have the same inode)

Seeing as how I use Maildir, this works great. It would work horriby for 
incremental backups of mbox though.

(This also works great for backing up an FSFS repository).


Ken Bloom. PhD candidate. Linguistic Cognition Laboratory.
Department of Computer Science. Illinois Institute of Technology.
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