After being moved, messages remain in both folders on the server

[Bron Gondwana]

On Fri, Mar 30, 2012 at 09:53:17PM +0200, Eric Luyten wrote:
> On Fri, March 30, 2012 12:26 pm, Adam  Tauno Williams wrote:
> > On Thu, 2012-03-29 at 12:12 -0400, Mikhail T. wrote:
> >
> >> I just noticed, that, when I move a message from INBOX to a folder in
> >> Thunderbird (via IMAP), the file on the server sometimes remains in
> >> both directories: /var/spool/imap/user/mi/message.
> >> and /var/spool/imap/user/mi/folder/message.
> >> The copies are a hardlink, so little space is wasted, but I'm
> >> concerned about the toplevel (INBOX) directory having too many entries... I
> >> thought, this is related to the folder (not) being immediately "compacted",
> >> but even when I explicitly request a compacting (in Thunderbird), the
> >> strangeness remains. Right now out of the 35170 messages in my INBOX, 1219
> >> are hardlinked to other folders... Is this normal? I'm using Cyrus imapd
> >> 2.4.11 on FreeBSD. Please,
> >> advise. Thanks!
> >
> > If Delayed Expunge is enabled, then it is normal.  Delayed expunge makes
> > restore of lost messages easier, is a handy means of 'data retention', and
> > helps to avoid I/O-explosions.  If Delayed Expunge isn't enabled - then this
> > seems odd.
> 
> Adam,
> Mikhail,
> 
> We do not have delayed expunge enabled on our 2.3.16 server and occasionally
> come across multiple-linked message files.
> I haven't been able to trace this back to one or another IMAP client, though.

Copy will cause it.

Replication failure will leave a link in the sync. directory until you clean
up.

Failed APPEND at the wrong time will leave a link into the stage. directory.

And of course a regular delivery to more than one person will cause it too.

Bron.