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Re: Threads and &



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On Thursday, June 18 at 10:08 PM, quoth Marianne:
>> Unfortunately, many of the more creative and powerful tricks mutt 
>> can perform with messages (e.g. connecting threads) rely on being 
>> able to modify messages on the IMAP server---which (because IMAP 
>> provides no method for modifying a message directly (for very good 
>> reasons)) involves copying messages and DELETING the old ones.
>
> Thanks! That's the explanation that must underlie this problem.  It 
> explains both that when I directly access Gmail via IMAP it removes 
> the label, and that offlineimap deletes the mail.  I didn't know that 
> mutt does delete + copy instead of modifying the message in place.

The reason for it is actually somewhat interesting. Essentially, IMAP 
provides two important message-related guarantees: that every message 
has a unique identifier (UID number) and that every unique identifier 
applies to exactly one message. The idea is to facilitate client-side  
message caching. For example, clients can ask the server "what 
messages are in this mailbox?", receive back a list of UIDs, compare 
that to its own list of cached message UIDs, and know which ones (if 
any) are new. If a message could be modified, it would have to receive 
a new UID so that any other clients would know that their cached copy 
of that message is no longer valid. Keep in mind that an IMAP server 
has to handle lots of annoying situations, such as when one client 
wants to update a message and another client wants to delete that same 
message at the same time. Similarly, there would be safety issues with 
multiple clients trying to modify the same message at the same time. 
Which change wins? How do you inform the others that the message has 
changed out from underneath them? That sort of thing.

Because of that, IMAP doesn't have a "modify message" command (okay, 
if we spent enough time on it, we can probably work out some 
complicated new semantics for how such a thing might work... but 
that's the basic reason IMAP doesn't have one, as I understand it). On 
the other hand, IMAP *does* have a command for adding a whole new 
message to a folder ("APPEND"), and has a command for removing a 
message from a folder ("DELETE"). So mutt does what it needs to do in 
order to accomplish what it wants done.

>> When you run into trouble while using something like offlineimap, 
>> my first suggestion would be: try doing it without offlineimap. If 
>> it works, then you have isolated the problem: it's an offlineimap 
>> problem. If it still doesn't work, then you have eliminated a 
>> potential cause, and you've made progress toward figuring out what 
>> the real problem is.
>
> Fully aggree, and again, if you look at my initial post from December 
> 2008 you'll find that that's what I did.

Ahh, I missed that part.

> Thanks again for your explanations about Gmail & IMAP and what mutt 
> does when it links threads, that really cleared things up for me.

Glad to help!

~Kyle
- -- 
It is only possible to live happily ever after on a day-to-day basis.
                                                    -- Margaret Bonnano
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