Monthly Archives: March 2011

Outlook 2007: Poor Performance and Planning Ahead

We are seeing a lot of support requests relating to poor Outlook performance, many of which involve running Outlook 2007 against an Exchange Server 2003 back end. To try and head some of these off, here is a review of the literature available and an explanation as to why it is important to understand how these things may affect your estate before you upgrade a large number of users from Outlook 2003 to 2007.

You will certainly want to read and understand the following three articles before doing anything :

Personal folder files are unsupported over a LAN or over a WAN link

OK. It’s not Outlook 2007. It’s not Exchange Server 2003. However, if you’re doing this, stop it. Now. We can’t support you.

Plan an upgrade to Outlook 2007

How Outlook 2007 works with different Exchange Server versions

Make sure that your Solution Architect is fully conversant with these. Ask them questions.

Performance Issues that may be experienced after upgrading.

How to troubleshoot performance issues in Outlook 2007

This article describes a range of issues which will cause Outlook 2007 to perform poorly. The gotcha is that a number of them will also cause the connected Exchange 2003 server to perform poorly. Ones to particularly watch out for are:

Are you running the latest version of Outlook 2007? Sp2 is the bare minimum. See for reasons why.

Do you have many items in a single folder? This has a particularly large impact on Exchange if you’re not running in cached mode. See the article below.

Do you have any non-essential add-ins or out-of-date add-ins that are installed in Outlook?

Did you install any gadgets that integrate with Outlook? One for Windows Vista users.

Did you install Windows Desktop Search on a Windows XP-based computer or install Outlook on a Windows Vista-based computer? Exchange HATES Desktop Search.

Are you running Outlook with the To-Do Bar enabled when Outlook is running in online mode against an Exchange server?

Outlook users experience poor performance when they work with a folder that contains many items on a server that is running Exchange Server

The article discusses how this impacts the client – be aware that it is also affecting disk I/O, CPU cycles and RPC requests on the server itself. RPC requests can have a significant impact on the amount of paged pool memory available to the server, and cause instability as well as poor performance on Exchange 2003. 5000 items is very much a finger in the air number – you may see problems with item counts well below this. See this article for more details and some sound advice – remember, it’s not the client that experiences the performance issue here, it’s the server.

Client performance can be an issue in cached mode, however.

You may experience performance problems when you are working with items in a large .pst file or in a large .ost file in Outlook 2007;EN-US;932086

This is more of a problem with RTM and SP1 versions of Outlook 2007. The article on SP2 improvements gives more detail on how much better things are. There’s some useful information on configuring sizes here:

An Exchange Server 2003 server that hosts many Outlook client sessions may run out of paged pool memory

Due to the increased number of connections that Outlook 2007 may open, it may be necessary to apply this patch, which will reduce the number of allocated tokens.

You may experience poor performance when Outlook 2007 connects to an Exchange Server 2003 server;EN-US;949295

This can be a real problem, and, as you can see from the article, the fixes are not pain-free; either change the way your users behave or upgrade your Exchange servers. A knowledge of shared calendar usage will be invaluable before any upgrade plan goes ahead. Outlook 2007 caches non email shared folders. Outlook 2010 caches ALL shared folders. Ouch. See for more details on this.

Your Exchange Server 2003 computer may stop responding after a MAPI client opens more than the default value of certain server objects

There are a number of causes for the dreaded 9646 error – the solution is, in our experience, almost never to increase the number of connections or objects. You always need to understand why your clients are requesting more than they should – we have found that it is usually a third party product causing this, and quite often an unauthorised one. See also:

The second article contains good advice on preventing users adding large mailboxes to a cached exchange mode profile in outlook 2007, which can also be a major cause of pain.

Not performance problems, as such, but gotchas, for sure.

How Outlook 2007 uses the forms cache and how to troubleshoot forms cache problems

The forms you use with Outlook 2003, that are stored on the Exchange server, may not work properly with Outlook 2007.

Two articles on cached mode: – how it works in outlook 2003 – how it works in 2007 and 2010.

You’ll need to understand the differences, and the impact these may have.

Administering the offline address book in Outlook 2003 and Outlook 2007

Sooner or later the OAB will raise its ugly head. This article will help.

Error: “Trying to connect to Microsoft Exchange Server” results in MAPI_E_LOGON_FAILED

If you’ve already upgraded your GC/DC infrastructure to Windows Server 2008 then you may come across this when you move to Outlook 2007 on Exchange Server 2003. Or before, in fact.

How to troubleshoot missing and duplicate appointments in Outlook

More a problem when you start to integrate “handheld” devices, but as this sometimes goes hand in hand with an Outlook 2007 rollout, I thought I’d include it.

Description of common scenarios in which Calendar information may be removed from the Calendar or may be inaccurate

…and this is a similar article for other calendar problems.

Memory or performance problems looping through items

This can be a problem if you’ve written a bit of vbscript into a custom form, or if you’re using a third party add in. It works the same in 2007 and 2003, as far as I am aware.

The program stops responding when you try to open or to save a file in an Office 2002 program, in an Office 2003 program, in an Office 2007 program, or in an Office 2010 program

Ok, the problem isn’t unique to Outlook 2007, but the error message is, so you may experience it as part of an upgrade. WAN links are often the culprit, we find.

Microsoft Outlook 2007 may experience Send/Receive or performance issues after a recent update has been installed on the computer

Hopefully by the time anyone gets this far down, the problem will be irrelevant.


Be careful upgrading to Outlook 2007. We would advise a programme of performance monitoring, and the use of capacity monitoring tools like exmon as part of your project. We’d also recommend that these tools are used throughout a phased project, rather than moving all users in one big hit. Remember, if you don’t know where you are, you can’t get to where you’re want to be.

Other useful articles:

Support For Microsoft Outlook 2010 and 2007 technical problems

Not an article as such, but a directory of useful resources.

Outlook RPC Dialog Box Troubleshooting

This article is the daddy. Really. Everything you ever wanted to know about pop up boxes.

Troubleshooting error messages that you receive when you try to send and receive e-mail in Outlook and Outlook Express