linux-kernel - Re: Query: Patches break with Microsoft exchange server.

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Message-ID: <1281542305.5107.11.camel@localhost>
Date:	Wed, 11 Aug 2010 16:58:25 +0100
From:	David Woodhouse <dwmw2@...radead.org>
To:	Jeffrey Hundstad <jeffrey.hundstad@...u.edu>
Cc:	viresh kumar <viresh.kumar@...com>,
	Felipe Contreras <felipe.contreras@...il.com>,
	"git@...r.kernel.org" <git@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"Justin P. Mattock" <justinmattock@...il.com>,
	Uwe Kleine-König 
	<u.kleine-koenig@...gutronix.de>,
	Valeo de Vries <valeo@...eo.co.cc>,
	Linus Walleij <linus.ml.walleij@...il.com>,
	Matti Aarnio <matti.aarnio@...iler.org>, mihai.dontu@...il.com,
	richardcochran@...il.com, "Gadiyar, Anand" <gadiyar@...com>
Subject: Re: Query: Patches break with Microsoft exchange server.

On Wed, 2010-08-11 at 10:46 -0500, Jeffrey Hundstad wrote:
> Exchange 2010 does not handle IMAP "chunking" (partial message transfer) 
> correctly.  Any request after about 1 megabyte of total message size 
> will fail.
> 
> Thunderbird uses this "chunking" feature to give you a status update 
> while downloading large messages.  The IMAP statements are of this type:
> 11 UID fetch 244477 (UID RFC822.SIZE BODY[]<20480.12288>)
> 
> When the 20480 is larger than 1MB Exchange "claims" there is no more.  
> Sigh.... 

I think the problem is not with the fetching -- the problem is that
Exchange lies about RFC822.SIZE before the IMAP client even starts to
fetch the message. It reports a size which is smaller than the actual
size of the message, thus leading to truncated fetches.

In Evolution we have a workaround -- we don't just stop when we get to
the reported RFC822.SIZE; we continue fetching more chunks until the
server actually stops giving us any more. It's not as efficient (because
we fall back to having only one more chunk outstanding at a time rather
than the normal three in parallel), but at least it works around this
brokenness of Exchange.

http://git.gnome.org/browse/evolution-data-server/commit/?id=9714c064

-- 
David Woodhouse                            Open Source Technology Centre
David.Woodhouse@...el.com                              Intel Corporation

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