Disappearing e-mail from numbered (e.g. "2008") IMAP folders

I'm not sure exactly where my point of failure is, so I thought I'd
send out a general call for advice on Usenet. If I'm posting in an
inappropriate place, please let me know a more appropriate place to
post. Obviously I've Googled for an explanation and haven't found one
yet.

I have several different offices, each running a different version of
Cyrus IMAP. The other common denominator is a Blackberry handheld
device and the Thunderbird e-mail client, all different versions on
the users with these symptoms.

In the last 4 months or so, I've been getting complaints that the
contents of several users' numbered folders have disappeared.

Here is an example namespace for such a mailbox:
user.name.backup.2004
user.name.backup.2005
user.name.backup.2006

These folders might have had thousands of messages, and are now empty
(with the exception of Cyrus's index and cache files in the
filesystems). I can't figure out what has changed in that time, and
the problem doesn't appear to have extended to other folders, (for
example Sent and Drafts).

I have eliminated the possibility of a security compromise, since this
has happened randomly on various sites with no common passwords, and
the problem appears clearly programmatic.

The naming convention of using a numbered folder name has been used
for at least 3 years (probably 4 or more) on one of these servers, and
since the problem couldn't have occurred before 2007 I guess I can
eliminate Cyrus as a cause.

If the problem has to do with Thunderbird, I'd be absolutely amazed
since they have a very vocal user base and I searched hard enough that
I should have stumbled upon a similar complaint.

Is the most likely diagnosis that Blackberry's "web client" is the
cause of this problem?

Any advice, musing, or random guess would be greatly appreciated.

Thank you,
Daniel

On Wed, 26 Mar 2008, djbelly@gmail.com posted:
> If the problem has to do with Thunderbird, I'd be absolutely amazed
> since they have a very vocal user base and I searched hard enough that
> I should have stumbled upon a similar complaint.

For what it's worth, Thunderbird has a number of bugs in its IMAP support,
including not being able to support half of the possible UID space. I
have no idea what caused your problem (and no software that I wrote seems
to be in the loop), but don't assume that it can't be a Thunderbird
problem.

-- Mark --

http://staff.washington.edu/mrc
Science does not emerge from voting, party politics, or public debate.
Si vis pacem, para bellum.

On Mar 26, 5:29*pm, Mark Crispin <M...@Washington.EDU> wrote:
> On Wed, 26 Mar 2008, djbe...@gmail.com posted:
>
> > If the problem has to do with Thunderbird, I'd be absolutely amazed
> > since they have a very vocal user base and I searched hard enough that
> > I should have stumbled upon a similar complaint.
>
> For what it's worth, Thunderbird has a number of bugs in its IMAP support,
> including not being able to support half of the possible UID space. *I
> have no idea what caused your problem (and no software that I wrote seems
> to be in the loop), but don't assume that it can't be a Thunderbird
> problem.
>
> -- Mark --

Thank you kindly for creating my very favorite electronic mail
protocol, and for your advice. I decided to take a look at users
without Thunderbird and otherwise similar usage patterns to the two
others who had this trouble. The user is a Blackberry user with
several numbered folders and Outlook, and had no mysteriously emptied
folders.

Thanks,
Daniel