Outlook All Versions

By default, Outlook places each Offline Folders (.ost) file and Personal Folders (.pst) file that it creates in the %userprofile%\Local Settings\Application Data\Microsoft\Outlook folder. You can either use a registry value to change that default location, or you can manually create a new profile and specify the .ost filename and folder.

• .ost = offline folders file
• .pst = personal folders file

more details...

On a default Outlook / Exchange configuration, the user wont have a pst file, but an ost file. All the stuff in their inbox will be on exchange and in the ost file. If they want to back it up, they can export it to a pst file.

OST - Offline Folder Storage - A file that contains a local replica of a user's Microsoft Exchange Server-based folders (private and public) and forms. The OST is synchronized with the Microsoft Exchange Server copy for use while working offline. An OST is specific to a particular mailbox and cannot be accessed by other users of Microsoft Exchange Server.

PST - Personal Folder Storage - A file that may contain folders, messages, forms, files and other items. You can create any number of PSTs for use with a single profile. You can also designate a PST as the delivery location for incoming mail.

New Client Installation - If you are installing the Microsoft Exchange client for the first time, during the profile creation you will be asked if you travel with the computer. If you answer yes, an Offline Store provider is set up for you and a file, Exchange.ost, is created. The OST is where the offline folders will be stored.

Existing Client Installation - If this is an existing installation of the Microsoft Exchange client, you can create an offline store using the Offline Folder File Setting button in the Advanced tab of the Microsoft Exchange Server driver property page. If multiple users will be using a single computer, each user needs his or her own OST file.

Change the location where your offline files are saved - Outlook 2003

1. Exit Outlook.
2. Click Start, and then click Control Panel.
3. Double-click Mail, and then click E-mail Accounts.
4. Click View or change existing e-mail accounts, and then click Next.
5. Select the Microsoft Exchange Server account, and then click Change.
6. Clear the Use Cached Exchange Mode check box.
7. Click More Settings.
8. Click the Advanced tab.
9. Click Offline Folder File Settings.
10. Click Disable Offline Use, and then click Yes in the dialog box that appears.
11. Click Offline Folder File Settings.
12. Click Browse, go to the location where you want to save your .ost file, and then click Open.
13. Click OK.
14. Select the Use Cached Exchange Mode check box.
15. Click Next, and then click Finish.

Corrupted Data File / Mail Folder File

SCANPST.EXE is the Inbox Repair Tool provided by Microsoft and designed to sometimes automatically correct problems. Find it in the same directory that Microsoft Outlook is installed such as c:\Program Files\Microsoft Office. Launch it from file explorer and once running select the PST file. It will test the PST file for errors and give you a repair option if it finds one. Do not simply run it one time if it did indeed find errors. After each fix attempt you must run it again. Continue this cycle until it runs and finds no more errors. After about five runs it should have the job done. If not you will have to consider giving up.

SCANPST.exe is used to scan the Offline Data File (OST) of Outlook when used as an Exchange client in cached mode. This is only if you are connected to an exchange server. If you are a POP or IMAP user then disregard. Even if you use an Exchange server you probably don't care about the exchange cache file unless you have been away from the office and working offline.

Huge Over-Sized Data File / Mail Folder File

You can't save everything!!!! When all of the messages and attachments in your Outlook exceeds a certain point, right around the 2GB mark, Outlook becomes very ill. The Inbox Repair Tool can't help you if you have a 2GB or larger PST file and it is corrupted. Now we need to do a hatchet job and blindly chop off the bottom (or the oldest stuff if all goes well). This is not an ideal option but better than being locked out or losing it all.

PST2GB.exe will attempt to fix the situation by truncating the PST file so it will be at a manageable size. The truncated data is not recoverable. After you run PST2GB you'll want to run SCANPST against the file as many times as necessary to get a clean scan. Then fire up Outlook and see if you got lucky.

PST2GB is not included with our Outlook installation because Microsoft is afraid you might run with scissors in your hand. Download it from Microsoft. I would put the link here but about once a month Microsoft rearranges their web site and all links to Microsoft become broken (they are turds). Do a search for it and download from Microsoft only (no 3rd party web sites.)

Command Line Switches

Hold down the Windows Key and Press R to get the "run dialog" where you can launch Outlook using a command with switches (things you type after the command.) Here is an example:

outlook.exe /Resetfolders

This launches outlook with the command line switch "/resetfolders" Here are the various command line switches available:

   /Cleanreminders - fix calendar issues and delete all of the reminders or recreate them from your items.
   /CleanViews - Resets the Outlook views to the default set that Outlook comes with.  Can fix some Outlook startup crashes.
   /Resettodobar - If you have problems with the To Do Bar in Outlook 2007 or 2010 then use this switch to clean and regenerates the To Do Bar.
   /Resetfoldernames - Puts your default folders back to their original names.  This doesn't affect the content of the folders, just renames them.
   /Resetfolders - Create deleted default folders including any missing default folders at their original location.
   /ResetNavPane - Cleans and regenerates the navigation pane.  Can fix some Outlook startup crashes.

Microsoft Exchange Server

This document relates directly to the Exchange Server page.