[Dovecot] Outlook 2010 very slow when using IMAP - are there any tweaks?

[J E Lyon]

On 3 Jul 2012, at 08:12, Kaya Saman wrote:

> On Tue, Jul 3, 2012 at 7:59 AM, J E Lyon
> <role.Dovecot-Readers at jlassocs.com> wrote:
>> On 3 Jul 2012, at 07:46, Timo Sirainen wrote:
>> 
>>> On 3.7.2012, at 9.38, Kaya Saman wrote:
>>> 
>>>> So if I look at a different authentication mechanism say LDAP would it
>>>> improve performance?
>>> 
>>> I doubt authentication has anything to do with why Outlook downloads mails slowly.
>>> 
>>> But you could configure Outlook to use plaintext authentication instead of NTLM authentication to see if it makes a difference. No need to change anything on Dovecot side then.
>> 
>> It's a bit of a random tuppenyworth, but all my experience of slow Outlook clients seems to be local mail store sync work, perhaps garbage-collecting / defragmenting or something, but not actually getting the emails themselves . .
>> 
>> I have one particular client who reported issues yesterday as it happens -- all versions of Windows from XP thru Win7 running mostly older Outlook but a couple of 2010 clients -- and one particular user, logged in on only one particular workstation (Win7 & 2010 as it happens) experiences _colossal_ delays in waiting for mail to open or respond at times, and yet any other user, or moving to another machine, it's all swift and fine.
>> 
>> That smacks of a local desktop cache problem to me... All on the LAN, as well, no slow connections.
>> 
>> As I say, just 0.02 -- may not be overly relevant, but my instinct is that local storage with Outlook has significant possibility for issues.
>> 
>> J.
> 
> Hmm... interesting point and had I been using a 'standard' filesystem
> type I would have to agree.
> 
> 
> However this is a clean server with plenty of space left on the pool
> allocated for mail and it's additionally using ZFS too.
> 
> 
> The point is that I am monitoring using nload as well as other things
> and the maximum bandwidth being got with Outlook is a few Mbps burst,
> average 50kbps; while with T-Bird I get way over 130Mbps???

Oh, I may have come into the thread a little late and missed some details :)

All the same, the customer I was mentioning has a fairly newish machine, though nothing fancy filesystem-wise. Sounds like you're monitoring what's actually happening anyway.

Having said that, I've _always_ seen Microsoft network activity fall way below other protocols, so it might not be so surprising -- and if the local store is busy shuffling every message each time a new one is added, that would explain a lower load on the network while the local client was busy chasing its own tail.

Do you mean that the clean install has very little email saved locally yet, and that Dovecot has little content for it to retrieve? So, there surely couldn't be any local file thrashing, there...

J.