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Indiana University Bloomington

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Offline Folders in Outlook

Offline folders (.ost) files are stored on your computer and are available even when the network is down. The default location for the .ost is your current Windows folder. Like personal folders (.pst) files, .ost files can be compacted to save space on your computer.

The difference between an .ost file and a set of .pst files is that the .ost file starts as a mirror image of your folders on the Exchange Server, and works in conjunction with the Exchange Server during synchronization. A set of .pst files, on the other hand, is simply a storage location on your hard disk or a server other than the Exchange Server.

When you work offline, you can add, delete, and modify the contents of an .ost file exactly as you would with a folder on a server. For example, you can change and move items in your offline Inbox, send messages that are placed in your offline Outbox, and read your offline public folders. In the meantime, information on the server is still processing. You continue to receive new messages in your mailbox while other users can add, delete, and change items in public folders. However, you are not aware of these changes on the server until you connect to the network.

When you need to update the contents of the .ost file and its corresponding server folder so that they are identical, you synchronize the folders, and then continue to work offline. In Outlook 2002, this is done through Send/Receive Groups. Synchronization connects to the server through Dial-Up Networking, copy the changes made in each folder to the other folder, and then disconnect. An item that you delete from either the .ost file or the corresponding server folder is deleted from both after synchronization.

How to Create an Offline Folder File for Exchange Server

NOTE: You must be connected to the Exchange Server for the initial creation and synchronization of the .ost file.

Use the following steps to create an .ost file:

  1. On the Tools menu, click E-mail Accounts, click View or change existing mail accounts, and then click Next.
  2. In the Outlook processes email for these accounts in the following order box, click Microsoft Exchange Server, and then click Change.
  3. Click More Settings.
  4. On the Advanced tab, click Offline Folder File Settings.
  5. In the File box, type the path to the file that you want to use as the .ost, file. The default name is Outlook.ost. If this file already exists, you are prompted for a new name.
  6. Click OK
  7. Click OK again
  8. Click Next
  9. Click Finish

All of the standard Outlook folders (Inbox, Outbox, Deleted Items, Sent Items, Calendar, Contacts, Journal, Notes, and Tasks) on the Exchange Server are now ready for offline use.

How to Turn on Scheduled Synchronization

  1. On the Tools menu, click Define Send/Receive Groups.
  2. Click All Accounts.
  3. Under When Outlook is Offline, click to select Schedule and automatic send/receive every X minutes. Select whatever time that you want.
  4. Click Close.

How to Set Up a Primarily Offline Profile

  1. On the Tools menu, click E-mail Accounts.
  2. Click View or change existing e-mail accounts, and then click Next.
  3. In the Outlook processes email for these accounts in the following order box, click Microsoft Exchange Server, and then click Change.
  4. Click the More Settings button.
  5. Click When Starting, click the Manually Control Connection State option, and then click Work Offline and use dial-up networking under Default Connection State.
  6. On the Connections tab, verify that the Connect using my Local Area (LAN) option is selected.
  7. If Outlook is running, click Exit on the File menu, and then restart Outlook to begin working Offline. There will be a small icon in the lower right-corner indicating the offline state.

NOTE: You cannot use an .ost file that has previously been used with a different mailbox. If you do, you may receive the following error message:
The file <filename>.ost cannot be accessed because it has been configured for use with a different mailbox.

How to Synchronize a Specific Folder

To synchronize a specific folder, click to select the folder that you want to synchronize, point to Send/Receive on the Tools menu, and then click This Folder.

How to Synchronize All Folders

To synchronize all your offline folders, you can either click the Send/Receive button on the Standard toolbar, and then press the F9 key, or on the Tools Menu, point to Send/Receive, and then click Send and Receive All.

NOTE: When you synchronize, a log file appears as a message in your Deleted Items folder. This log file contains information such as the time you synchronized, the names of the folders synchronized, and the number of items added.

How to Automatically Synchronize All Folders When You Quit Outlook

Use the following steps to automatically synchronize all folders when you quit Outlook:

  1. On the Tools menu, click Send/Receive Settings, and then click Define Send/Receive Groups.
  2. In the Send/Receive Groups dialog box, click to select the Perform An Automatic Send/Receive When Exiting check box.
  3. Click Close.
  4. All folders that are set to be available while are offline are now automatically synchronized according to the options that you set. It is important to synchronize and download the Address book before you log off your Exchange Server when you travel. This is particularly important when you travel for the first time. This ensures that all your offline folders are updated before you leave.

Use the following steps to download your address book:
1. On the Tools menu, click Send/Receive, and then click Download Address Book.
2. Click to select the desired download options, and then click OK.