diTii.com Digital News Hub

Sign up with your email address to be the first to know about latest news and more.

I agree to have my personal information transfered to MailChimp (more information)


Exchange Server: Optimizing Outlook 2007 Cache Mode Performance for a Very Large Mailbox

My mailbox size is 7.4GB. I send/receive around 200 emails a day; so that 7.4GB of email goes back several years. I don’t use too many rules so most of my email ends up in my Inbox (30k items).

If you have read Exchange mailbox sizing guidance, you will notice that my mailbox size is higher than the recommended max OST size (2GB), and I store more items in my Inbox than the recommended (5k). Since I am one of the contributors to this guidance, I felt I should come clean (by writing this blog); and explain how I use my email that meets the following criteria:

  • Large Mailbox (several years worth of email stored in the Exchange Store)
  • No PST usage
  • Good laptop cached mode user experience
  • Good workstation/home computer cached mode user experience
  • The ability to search my entire mailbox
  • My email processing does not over burden the server

Before I get started, I should probably tell you what hardware/software I am using


Office Workstation

Home Computer


Windows Vista SP1 RC1 (x86)

2 core 2.66ghz

2 core 3.2ghz

2 core 2Ghz

Office 2007 SP1

4GB Memory

2GB Memory

2GB Memory


10K SCSI disk

7.2k SATA disk

5.4K SATA disk

*The software is the same across all machines.

**The disks sited are those which host my Outlook 2007 OST (I am the Exchange Storage Program Manager; I have lots of disks in all of my computers).

Not surprisingly, I have a different user experience processing my mailbox depending upon which machine I am on. Also not surprisingly, my experience has changed as my mailbox size has grown. As my mailbox began to exceed 2GB, I noticed that my laptop experience began to degrade. It took longer to sync down new messages, longer to do sorts etc. As my mailbox exceeded 4GB, I noticed the same thing on my home computer. I now experience the same slowness on my office workstation with my 7.4GB mailbox (don’t ask what my laptop experience is like). This is expected since each machine has a different performing hard disk (which my Outlook 2007 OST is stored on) and the fact that Outlook storage performance will slowly degrade as the mailbox size increases. Outlook development folks have the same max mailbox size as me (~10GB), so they are also very much aware of the performance issues associated with a large OST; and are working toward addressing the issue in future versions of Outlook. They made great progress in improving OST scalability with Outlook 2007 Sp1, but I hear there is still work to do.

My background is in software performance (especially storage performance); so I couldn’t live with the status quo. I was stuck, I needed my large mailbox; but I also needed a great/fast user experience so I could effectively process my mailbox. All of my machines had sufficient memory (2GB or more) so I couldn’t solve the problem by adding memory (to provide the Windows System Cache with more memory to buffer the OST IO’s). I basically had the following options:

Full Article

Exchange Server, Exchange Server 2007, Outlook, Cache, Optimization, Performance, Mailbox, Tips and Tricks

Share This Story, Choose Your Platform!

Get Latest News

Subscribe to Digital News Hub

Get our daily newsletter about the latest news in the industry.
First Name
Last Name
Email address
Secure and Spam free...