Microsoft Office Outlook 2007 momentarily stops responding during typical operations. This includes when you read e-mail messages, move e-mail messages, or delete e-mail messages.
These symptoms are most noticeable during mail delivery or during synchronization. These symptoms become more pronounced as store size increases. They are more likely to occur when the size of the .pst file or the size of the .ost file approaches 2 gigabytes (GB). Additionally, they are more pronounced in a very large .pst file or in a very large .ost file that is 4 GB or larger.
When you perform the same operations in earlier versions of Outlook, the same performance problems do not occur if the .pst file or the .ost file is large.
To accommodate new features, Outlook 2007 introduced a new data structure for .pst
files and for .ost files. In this new data structure, the frequency of writing
data to the hard disk increases as the
number of items in the .pst files or in the .ost files increases.Note
You cannot create a .pst file or an .ost file without this new data
To resolve this problem, install the update that is described in the following article in the Microsoft Knowledge Base:
Description of the update for Outlook 2007: April 13, 2007
Update 933493 is available to improve the general responsiveness of Outlook 2007 during common operations. These operations include reading, moving, deleting, and downloading e-mail messages for users who have large mailbox files (.pst files and .ost files) that are stored on their computers. From a technical perspective, this update optimizes the pattern in which Outlook 2007 writes to a large .pst file or to a large .ost file. This results in a reduction of disk access.
This update for Outlook 2007 is part of our continued commitment to improving our customers' product experiences. We are aware that some customers have encountered performance issues when they run Outlook 2007. This update incorporates several performance improvements. This update is designed to do the following:
- Reduce the time that is required to copy or to move messages from one folder to another folder.
- Increase the download speed when you download messages.
- Reduce the time that is required to delete messages.
You can also use one of the following methods to resolve or minimize this problem.
Video: How to reduce the .pst file size for Outlook
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Method 1: Reduce the size of the Exchange mailbox
If you reduce the size of the Exchange mailbox, the size of the .ost file will
also be reduced. To reduce the size of the Exchange mailbox, do one or more of
- Delete items in your mailbox.
- Archive items in your mailbox to one or more .pst
You can delete items or archive items manually. Alternatively, you can use Mailbox Cleanup. To
use Mailbox Cleanup in Outlook 2007, click
on the Tools
menu. In the Mailbox Cleanup
dialog box, you can
use any one of the following features:
- View mailbox size.
- Find items that are older than a specified number of
- Find items that are larger than a specified size.
- Move old items to the archive file by clicking
- Empty the deleted items folder.
- Delete all alternative versions of items in the
Method 2: Use an online mode profile instead of a cached mode profile
Cached mode profiles use an .ost file to store the mailbox locally
on the hard disk. If you have a large Exchange mailbox, you will have an .ost
file that is even larger. For example, if the mailbox size is 350 megabytes (MB), the .ost
file size can be 475 MB or larger.
Method 3: Split your large .pst file into several smaller .pst files
Outlook 2007 does not have a built-in function to split a .pst
file into multiple .pst files. Therefore, you have to use one of the following
steps to split a large .pst file:
- Use the Archive feature to move items to a new .pst file. To do this, follow these steps:
If you want to change the display name for this .pst file, follow
- In Outlook 2007, select your .pst file in the navigation pane.
- On the File menu, click
- In the Archive dialog box, click to
select the Archive this folder and all subfolders check box,
and then click a folder from the list.
- In the Archive items older than
drop-down box, click a date.
- Click Browse, specify a path and a file
name for the new .pst file, and then click OK.
Note The new .pst file is displayed in the Mail Folders list as
- Right-click Archive Folders, and then
- In the Archive Folders Properties
dialog box, click Advanced.
- In the Personal Folders dialog box,
enter the new display name in the Name box.
- Click OK two times to return to
- Use the Move to Folder feature to move items to a new .pst file. To do this, follow these steps:
- On the File menu, point to
New, and then click Outlook Data
- In the New Outlook Data File dialog
box, click Office Outlook Personal Folders File (.pst), and
then click OK.
- Specify a path and a file name for the new .pst
- In the Create Microsoft Personal
Folders dialog box, specify the display name of the .pst file in the
Name box. This is the name that is used by Outlook in the
Mail Folders list.
- In the folder that contains the items that you want to
move to a new .pst file, click one or more items to move.
- On the Edit menu, click Move
- In the Move Items dialog box, click
- In the Create New Folder dialog box, enter a name for the new folder in the Name box.
- Under Select where to place the folder, click the new .pst file, and then click OK.
- In the Move Items dialog box, make
sure that the new folder in the new .pst file is selected, and then click
Method 4: Use a filter to restrict the items that you synchronize from Exchange to your .ost file
To configure a synchronization filter
on a specific Exchange mailbox folder, follow these steps:
- Right-click the folder, and then click
- In the Properties dialog box, click the
- On the Synchronization tab, click
- In the Filter dialog box, specify the
criteria that will be used to synchronize new items that you want to arrive in this
- Click OK two times to return to
This method will reduce the current size of the .ost file. Items
that were previously synchronized in this folder will be removed from the local copy of your .ost file the next time that Outlook
synchronizes this folder. These items will be removed if they do not fit the filter
criteria. You may have to wait for background compaction to
occur before you can see the size of your .ost file decrease. Alternatively, you
can manually compact the .ost file by clicking the Compact Now
button in the Advanced settings of the Exchange account.
If you use a
synchronization filter, you can view the items that are not synchronized with
the .ost file either by using Microsoft Office Outlook Web Access or by using an Outlook client that is
configured to use online mode in an Outlook profile.
If you use a portable computer
If you are using a portable computer, you may experience these
problems sooner than you would on a desktop computer. This occurs because hard disks on portable computers are generally slower than hard disks on desktop computers. The
performance problems are directly related to hard disk speed. If you add more
random access memory (RAM) to a computer, there is no effect on this problem.
For more information about Outlook .pst files, click the following article numbers to view the articles in the Microsoft Knowledge Base:
The .pst file has a different format and folder size limit in Outlook
2007 and in Outlook 2003
How to configure the size limit for both (.pst) and (.ost) files in Outlook 2003
The registry path that is used in article 832925 is for Outlook 2003. For
Outlook 2007, use the \12.0
path instead of the \11.0
path that is mentioned in the article.