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

[Christoffer Dam Bruun]

I don't restore - I just recreate my chandler hub account and resync 
from there.
Part of the reason is that my crashes often have a precursor where 
chandler cannot exit because it
fails to properly write the .chex file :-)

So I concluded that "The Hub is your friend"

And since you have made it so *incredibly* smooth to create an incoming 
mail account, it is simply
faster to create it than to figure out where the latest account backup 
file is.

Best regards
Christoffer Bruun




Mimi Yin wrote:
> Wow, this is incredibly helpful Christoffer. We've been chasing this 
> bug for a long time.
>
> William, you were struggling with duped mail messages for a while. 
> Does Christoffer's repro steps sound like they apply to your issues as 
> well?
>
> Christoffer, how are you restoring your data after Chandler crashes? 
> Depending on how you're able to restore your data, there might be a 
> workaround to prevent mail dupes in the future.
>
> Mimi
>
> On Oct 10, 2008, at 5:06 AM, Christoffer Dam Bruun wrote:
>
>> 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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>