Reduce the size of the Outlook data file

Reduce the size of Outlook data files (.PST and .OST)

• After a long time of use, your Outlook mailbox will significantly "fill up". So every time you open Outlook, the process will open very slowly, or encounter many errors, even Outlook is suspended.

Is there a way to reduce the size of data files in Outlook?

1. Manage your mailbox

• Mailbox Cleanup is one of the useful tools used to view your mailbox and personal folders in Outlook.
• You can also store old messages in Outlook Data File (.pst) to empty the Deleted Items folder.

1. Click the File tab.

2. Click Cleanup Tools.

3. Click Mailbox Cleanup.

4. Follow the steps below:

- To view the total mailbox size and any other folder, click View Mailbox Size.

- To find old messages, select Find items older than n days, enter any number between 1 and 999, then click Find.

- To find large messages, select Find items larger than n kilobytes, enter any number between 1 and 9999, then click Find.

- To delete old messages in your mailbox to store in Outlook Data File (.pst), click AutoArchive.

Outlook Data Files (.pst) are stored in the Documents \ Outlook Files folder on your computer. If using Windows XP, the .pst file is saved in the My Documents \ Outlook Files folder.

- To view the size of the Deleted Items folder, click View Deleted Items Size.

- To "empty" the Deleted Items folder, click Empty.

- To view the Conflicts folder size, click View Conflicts Size.

- To delete the contents of the Conflicts folder, click Delete.

• If you delete items in Outlook Data File (.pst), the files will automatically be compressed in the background while Outlook is running but you are not using the computer.
• Also you can compress these items manually. Compressing Outlook Data File (.pst) will take a few minutes.

1. Delete any items you do not want to archive.

2. Open Folder List view.

In the bottom corner of the Navigation Pane, click the Folder List icon or press Ctrl + 6.

3. On the Navigation Pane interface, right-click the Deleted Items folder, and then click Empty Folder.

4. Click the File tab.

5. Click Account Settings, then Account Settings.

6. On the Data Files tab, click the data file you want to select, then click Settings.

7. Click Compact Now.

* Note:

You do not need to exit Outlook after compressing the Outlook Data File (.pst) file.

• Reducing the size of an .OST file greatly improves Outlook performance. This process does not delete any saved messages or items running Microsoft Exchange Server on your computer:

1. Delete any messages that you do not want to archive.

2. Open Folder List view.

In the bottom corner of the Navigation Pane, click the Folder List icon or press Ctrl + 6.

3. On the Navigation Pane interface, right-click the Deleted Items folder, and then click Empty Folder.

4. Click the File tab.

5. Click Account Settings, then Account Settings.

6. On the Data Files tab, click the data file you want to compress, then click Settings.

7. Click Compact Now.

* Note:

- To delete items from the online and offline folders, select the items and then select Delete.

- If you are using an Exchange account in Cached Exchange Mode, you only have the option of deleting items in the offline Outlook Data File (.ost) folder.

- By default, when you use Cached Exchange Mode, your favorite public folders will not be synchronized.

If you choose to synchronize public folders, the .OST capacity will increase significantly.