Isaiah | 19 Jan 06:34 2005

IMAP to IMAP sync and message timestamps

Hi,

    I noticed when I perform an IMAP to IMAP sync, message content doesn't
change anywhere.  Oddly, my MUAs notice a difference in some of the
messages all of the time.  They display an updated arrival date, in-line
with when the message was synchronized.

    This seemed a little odd to me, because I didn't notice it with IMAP to
Maildir and Maildir to IMAP.

    It seems to happen with small (<1000 messages) mailboxes and large
(>32000 messages) mailboxes.

    Subsequently re-sync'ing doesn't seem to help.

    Any recommendations on how I can track this down or help by providing
information would be greatly appreciated.

    Thanks!
--

-- 
    - Isaiah

Simon Guest | 27 Jan 10:51 2005

3 way sync?

Hi,

I'm losing email trying to do a 3-way mail sync.  However, I'm not
sure that what I'm trying to do is supported by offlineimap, so here
goes ...

I have a 3 machines:

1. Server, running MS Exchange

2. Desktop, storing mail in Maildir format, and serving this over IMAP
   using courier-imap.

3. Laptop, storing mail in Maildir format.

I have a folder on the server I want to sync to all machines.  So I
run offlineimap on the desktop, sync'ing mail from the server into
~/Maildir/.server.INBOX (say).

I run offlineimap on the laptop, sync'ing mail from the desktop into
~/Maildir.  And I also (on the laptop), use offlineimap to sync mail from the
server into ~/Maildir/.server.INBOX.  (Note the subset relation in the
folder hierarchy.)

Suppose some mail arrives on the server.  I offlineimap it onto the
laptop.  Now it's on both server and laptop, but not on the desktop.
If I now offlineimap laptop with desktop, rather than copying the mail
to the desktop, it gets deleted from the laptop.

Does this sound familiar?  Any helpful suggestions, or is there more
(Continue reading)

John Goerzen | 27 Jan 17:26 2005

Re: 3 way sync?

On Thu, Jan 27, 2005 at 09:51:08AM +0000, Simon Guest wrote:
> I'm losing email trying to do a 3-way mail sync.  However, I'm not
> sure that what I'm trying to do is supported by offlineimap, so here
> goes ...

> I have a 3 machines:

I have a similar setup...  a server, and then three workstations that I
use regularly, including one laptop.

> I run offlineimap on the laptop, sync'ing mail from the desktop into

Here's the problem, I think.  If you just point both your laptop and
your desktop to sync directly from the server, you should have no
trouble.

I would certainly not advise syncing a single folder with multiple
servers.  I've never tried that, but I can't imagine anything but bad
things happening :-)

It is fine to sync multiple clients with the single server, though.

-- John

Simon Guest | 27 Jan 18:31 2005

Re: 3 way sync?

At Thu, 27 Jan 2005 09:39:03 -0700,
Matthew P Barnson wrote:
> 
> On Thu, 27 Jan 2005 09:51:08 +0000, Simon Guest <simon <at> guests.plus.com> wrote:
> > I have a 3 machines:...
> <snip>
> > Suppose some mail arrives on the server.  I offlineimap it onto the
> > laptop.  Now it's on both server and laptop, but not on the desktop.
> > If I now offlineimap laptop with desktop, rather than copying the mail
> > to the desktop, it gets deleted from the laptop.
> 
> The only really sensible way I see this working is to synchronize both the
> laptop and the desktop directly to the Exchange server.  OfflineIMAP was made
> to synchronize IMAP to Maildir -- I've never heard of it being used to
> synchronize Maildir to Maildir.

I'm already doing IMAP to Maildir, using courier-imap on the desktop.
Sorry if this wasn't sufficiently clear.

> I *think* this should work safely; I can't think of a situation off the top of
> my head where you'd lose data in such a 3-way sync.  However, I haven't tried
> it; I use offlineimap a lot, but I've heretofore always synched multiple
> clients to the same server source.

I don't recommend you do try it.  It doesn't appear to work safely!

cheers,
Simon

(Continue reading)

Simon Guest | 27 Jan 18:33 2005

Re: 3 way sync?

At Thu, 27 Jan 2005 10:26:31 -0600,
John Goerzen wrote:
> 
> On Thu, Jan 27, 2005 at 09:51:08AM +0000, Simon Guest wrote:
> > I'm losing email trying to do a 3-way mail sync.  However, I'm not
> > sure that what I'm trying to do is supported by offlineimap, so here
> > goes ...
> 
> > I have a 3 machines:
> 
> I have a similar setup...  a server, and then three workstations that I
> use regularly, including one laptop.
> 
> > I run offlineimap on the laptop, sync'ing mail from the desktop into
> 
> Here's the problem, I think.  If you just point both your laptop and
> your desktop to sync directly from the server, you should have no
> trouble.

Yes indeed - I have done this previously, and it works nicely.

> 
> I would certainly not advise syncing a single folder with multiple
> servers.  I've never tried that, but I can't imagine anything but bad
> things happening :-)

Yes, I have seen these bad things.  My motivation was for when I had a
secure connection from laptop to desktop, and from desktop to server,
but not from laptop to server.  Trying to use the desktop as a staging
post doesn't seem to work!
(Continue reading)

John Goerzen | 27 Jan 19:39 2005

Re: 3 way sync?

On Thu, Jan 27, 2005 at 05:33:46PM +0000, Simon Guest wrote:
> Yes, I have seen these bad things.  My motivation was for when I had a
> secure connection from laptop to desktop, and from desktop to server,
> but not from laptop to server.  Trying to use the desktop as a staging
> post doesn't seem to work!

It would if you only ever synced your laptop to your desktop.

The problem is that you are sometimes syncing the laptop to the server.
You are effectively introducing two different sets of UIDs into the
system, and looping back and forth with them.  I suspect you saw lots of
duplicated mails :-)

You might also find it useful to establish a ssh session to the desktop,
if that's secure.  But if you're on a secure link to the desktop, and
it's on a secure link to the server, shouldn't your laptop already have
a secure link to the server?

Simon Guest | 27 Jan 23:49 2005

Re: 3 way sync?

At Thu, 27 Jan 2005 12:39:26 -0600,
John Goerzen wrote:
> 
> On Thu, Jan 27, 2005 at 05:33:46PM +0000, Simon Guest wrote:
> > Yes, I have seen these bad things.  My motivation was for when I had a
> > secure connection from laptop to desktop, and from desktop to server,
> > but not from laptop to server.  Trying to use the desktop as a staging
> > post doesn't seem to work!
> 
> It would if you only ever synced your laptop to your desktop.
> 
> The problem is that you are sometimes syncing the laptop to the server.
> You are effectively introducing two different sets of UIDs into the
> system, and looping back and forth with them.  I suspect you saw lots of
> duplicated mails :-)
> 
> You might also find it useful to establish a ssh session to the desktop,
> if that's secure.  But if you're on a secure link to the desktop, and
> it's on a secure link to the server, shouldn't your laptop already have
> a secure link to the server?

You make some good points, and I now think I understand the problem.

As to your last point, my desktop to server link is only secure for a
certain definition of secure.  Actually, it's insecure, plain IMAP
over the public internet, but I happen to know the route it takes goes
through only nodes which I trust.  My server doesn't support IMAP over
SSL, nor can I tunnel over ssh.  So I'm slightly constrained.

Thanks for your input.
(Continue reading)


Gmane