[chandler-users] emails reappear in dashboard - can this be prevented

Christoffer Dam Bruun cdbruun at flyingpigs.dk
Fri Oct 10 05:06:20 PDT 2008

Hi Grant,

Here is how I can reproduce the problem (1.0.2):
1: File->Accounts
2: choose Incoming mail account
3: Delete account
4: Create new account - incoming mail
5: configure text fields
6: Press Auto configure - (this works for me) Apply settings
7: Press Configure chandler folders ( OK already set up)
8: Press Test - OK
9: Ok
10: File->Sync->Mail   - OK no new messages
11 Press "green circle of 2 arrows" icon on chandler desktop
- The I get a new version of all emails in "Chandler Mail" on the dashboard

Whenever Chandler crashes I usually lose my account settings, so email 
account recreating is not that rare.

Best regards
Christoffer Bruun
Grant Baillie skrev:
> On 8 Oct, 2008, at 11:32, Christoffer Dam Bruun wrote:
>> Hi Mimi,
>> Monday morning I suffered at mktime related crash and had to recreate my
>> account settings .
>> I do not remember seeing the duplicates before wednsday.
>> Question: What does chandler use to decide whether mails have been seen
>> before ?
>> Does it use any aspect of the imap account settings or *only* the
>> contents of the mails ?
> Hi, Christoffer
> Basically, the mechanism is standard for IMAP mails: all messages 
> within a mailbox carry a unique integer ID (an IMAP UID) that IMAP 
> servers guarantee increases with time (i.e. when new messages are 
> added to the mailbox, they have higher UIDs than older). For each 
> mailbox, Chandler tracks the highest UID it last downloaded, and only 
> downloads messages whose UIDs are greater than that.
> So, there are a couple of ways duplicates can theoretically happen:
> (1) Chandler somehow forgets that highest UID, and re-downloads 
> messages it has seen before. This would be a bug, of course. I had 
> thought this might be happening during an export/reload of your data, 
> which would explain why people see it occasionally, but in the test I 
> just did, this is not the case.
> (2) There's a mechanism in IMAP to handle the case where you delete 
> and recreate a mailbox. The mailbox itself carries a unique ID 
> (technically, it's called UIDVALIDITY): if this value changes, mail 
> clients are supposed to throw out their existing messages and start 
> again from scratch. If for some reason this occurs, I can believe this 
> would (incorrectly) lead to duplicate messages.
> At this point, I'm more inclined to believe (2). However, the only way 
> I can see it happening are either a buggy server, or if you moved 
> mailboxes around on the server from another client. I also suppose (1) 
> could happen if you deleted and recreated that IMAP account in Chandler.
> --Grant

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