ANSWER:

Omri – your solution does not work for IMAP accounts, because you can’t choose the folder for incoming mail on IMAP account.
Peter – this will probably work for future accounts and data files, but not solve the problem.

I have found a solution, a bit tech-intense, but working – on Microsoft Technet (thanks VONAH):

If you have moved the file you probably has now a new problem: “Error 0x8004010F: Outlook data file cannot be accessed” (NOTE: this solution edits your computer registers. Be carefull!)

1. Close Outlook. Click on Start then type regedit to open the register
   editor;

2. Go to “HKEY_USERSS-1-5-21-2252105952-3583732995-3196064763-1000SoftwareMicrosoftWindows
   NTCurrentVersionWindows Messaging
   SubsystemProfilesOutlook9375CFF0413111d3B88A00104B2A6676″

3. Right click on this folder and Export to save the actual
   configuration.

4. Find the folder (or folders if you have more than an account) that has
   the “Delivery Store EntryID” key.

5. Right click on “Delivery Store EntryID” key and than Modify.

6. The data in the key is in HEXA. On the righter column you will find the
   data in normal chars. Go to the end
   and find the path to the original data
   file. Edit it pointing the entire path
   to new folder of the file.

7. Open Outlook and everything is working again!

8. If any problem comes up, click on the file you exported to restore the
   orginal register settings.

Couple of tips to this solution:

1. You have to replace S-1-5-21….. key with the one that exists on your system (is it HKEY_CURRENT_USER?).

2. When editing path in binary data value, make sure you replace letters of old path with new letters and leave 00 values in place. If you need to add extra characters, add character, followed by 00 (assuming the character is in ASCII). The path must terminate with a couple of “00″ characters, for a total of 3 “00″s at the end of the value.

Alternately, in order to avoid editing binary data, just delete Delivery Store EntryID key, and next time you open Outlook, it will recreate the key with the correct folder info.

by Igor from http://superuser.com/questions/247700