Outlook Data File Cannot Be Accessed - Error 8004010F

Outlook Cannot Be Able To Send Message and gives a error message:

message: 'xxxxxj@xxxxxx.com - Sending' reported error (0x8004010F) : 'Outlook data file cannot be accessed

Outlook knows where the .pst file is as I am looking at it now - but for some reason it can't send nor receive.

The problem may occur when you moved the PST File to another location, or when you upgraded your outlook from older version to 2010. Anyhow, you can put a PST in any folder where you have read/write access. If, when you moved your PST, you overwrote a PST of the same name, then you've corrupted your mail profile and need to create a new one. If you did not overwrite a PST of the same name, make sure the PST is in a folder where you have the appropriate permissions. If that checks out as well, try a new mail profile.

Important: If you do decide to do the System Restore keep in mind that it won't move your PST file back to wherever it was. When you start up Outlook 2007 you'll probably have to point it to the new location of the PST file.

This is the solution (From Technet). 

Following these steps may fix the problem and Outlook will immediately began send and receive without having to reboot, close and re-open Outlook.  

Important: Before you bother creating new PST files / importing PST files or other laborious tasks, PLEASE READ THE FOLLOWING...

Take a look at where each of your email accounts is delivering mail. I think you'll find that after migrating to Outlook 2010 or Windows 7, the location is missing. So here are two fixes that will depend on your situation.

1. Click File (top left) /Account Settings. Select an account. If you're lucky, you can simply click the button that says Change Folder, select where you want the mail delivered and your done!
2. If you not that lucky, you will have to recreate each account with one important adjustment from what you are accustomed to. Delete and create each account one by one. When you're creating the new accounts select Manually Configure Server Settings and on the Internet Email Settings page you will see a box in the lower right corner that says "Deliver New Messages to:" New or Existing Outlook data file. Select Existing, Browse to your file location and select your data file. After completing the account set up process you should be in business!

Changing the folder to specify Inbox fixed the issue. Apparently the inbox did not get set and the higher level file name was selected.

1. From Outlook 2010 click File- Account Settings>Account Settings
2. Click Change Folder
3. Click the + to the left of the folder name to expand the subfolders. Click Inbox. Click OK.
4. Close Account Settings and click send/receive.

Try This Too:

1. Go To Control Panel
2. Find The Option Mail.
3. Click on email accounts and delete the account giving the error.
4. Recreate the account BUT manually. Then point it to the existing PST which You know was fine.
5. Set the recreated account as default.

Read More : http://social.technet.microsoft.com/Forums/en/outlook/thread/0acbed9c-de08-40f7-a77e-2cd0e626d9cb