[Dovecot] prevent dovecot from modifying maildirs

[Timo Sirainen]

On Fri, 2013-08-09 at 21:12 +0200, Felix Rubio Dalmau wrote:
> Michael, Charles,
> 
> 	thank you for your comments. I had already seen the wikipedia entries about ZFS, but when I have performed my tests, consisting in: generate a program that writes a 100 MB file to disk and perform the snapshot during the file is being written. Obviously the snapshot shows a view of the file with the information and size it had at the time of the snapshot... so I get a portion of it.
> 
> 	In order to save space I prefer no to have such half-files (mails) , and it is for this reason that I am asking if there is any way to prevent this.

If you don't disable mail_fsync, you won't get partially written mails.
And I'm not sure if you get them even if you do disable mail_fsync. The
mails are first written to temporary files, fsynced, then renamed to the
final name. So you might end up with some temporary files, but they
won't be visible and they'll be deleted automatically.

The above applies to all mailbox formats except mbox.