[Dovecot] SORT using cached filesystem modtimes

[Emmett Lazich]

Thanks Timo. Very interesting and very good by you.

My only followup thought is to ask: Is it possible for an IMAP client to
request a server side SORT, but not specify explicitly which date to
use, and thus rely on a server side choice of the SORT key? In which
case could Dovecot use the Date-header as the default SORT key?

On Mon, 2005-04-18 at 02:35, Timo Sirainen wrote:

> On Fri, 2005-04-15 at 15:31 +1000, Emmett Lazich wrote:
> > Timo or anyone,
> > 
> > This may be a bug or maybe a design decision. Either way I am curious
> > to hear comments.
> > 
> > Why do the dovecot-0.99.14 server's .imap.index files contain a cached
> > copy of each message's date and time as supplied by the filesystem, as
> > opposed to the date and time found in each message header?
> 
> There are two dates with IMAP. INTERNALDATE is one and Date-header of
> the message is another. The filesystem timestamp that you see cached
> in .imap.index.data file is the INTERNALDATE. The message's Date-header
> is also cached in the beginning of ENVELOPE data.
> 
> > When testing various imap clients (eg. tbird-1.0.2, evolution-2.0,
> > outlook2003, squirrelmail-1.4.4) I was intrigued by the behaviour of
> > message date sorting. I toggled on/off the use of server side SORTing
> > in some imap clients, then started forcing rebuilds of .map.index
> > files, and eventually came to the above conclusion.
> 
> Server side sorting supports sorting based on both INTERNALDATE
> ("ARRIVAL") and Date-header ("DATE"). It's client's choice which one it
> wants to use.
> 
> > For normal dovecot server side processing, this condition (if I am
> > correct) may not be a problem, but if someone was to deposit a bunch
> > of maildir files firstly into an imap account (bypassing dovecot), and
> > if this person (eg. me) did not preserve the filesystem/inode file
> > attributes. Then dovecot appears to cache the "wrong" data. What
> > happens then is that some imap clients can display wrong date+times in
> > the message lists, and some imap clients find that server side SORTing
> > does not work.
> 
> It all works correctly from Dovecot's point of view, because the
> messages arrived in the mailbox at that time..
> 
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