While its often a good idea to move a *.PST used by POP3 accounts to an easier to find locations, it’s less useful to move IMAP accounts. You don’t need to back it up, since its just a copy of you mailbox, which is stored on the IMAP server. If you need to move the *.PST, it is possible.
First, close Outlook then make sure Outlook is not listed in Task Manager, Processes tab a few minutes after you close it.
1. Open the profile (Control panel, Mail) and click on Data files.
2. Select the IMAP acct and click Open Folder to open the folder containing the PST.
3. Move the PST to the desired location.
4. *Do not rename the file* Outlook creates a new file in the default location if you try to rename it – you can only move it.
5. Switch to the Data Files window and double click on the account's data file.
6. Now you'll get the 'can't find' error and can tell outlook where to find it.
7. Close the dialogs and you are ready to restart outlook.
This will work with SharePoint and Internet Calendars, as well as HTTP accounts. You can’t move Outlook Connector message stores for Hotmail/MSN/Live accounts. In my experience, its mostly reliable but the new path occasionally gets forgotten and a new *.pst is made in the default location.
This works (and was tested) with Outlook 2003 and 2007.
Update: You can use this method to move POP3 data files as well.
Published October 28, 2008. Last updated on September 2, 2013.