Outlook Express Inbox full-Error Ox800C0131

You can fix your Inbox for free. Getting messages out of the current Inbox is another story.

Tools | Options | Maintenance | Store Folder will reveal the location of your Outlook Express files. Write the location down and navigate to it in Windows Explorer or, copy and paste it into Start | Run.

In WinXP, Win2K & Win2K3, the OE user files (DBX and WAB) are by default marked as hidden. To view these files in Windows Explorer, you must enable Show Hidden Files and Folders under Start | Control Panel | Folder Options Icon | View, or in Windows Explorer | Tools | Folder Options | View.

With OE closed, find the Inbox.dbx and rename it to Inboxold.dbx.  A new Inbox will be created automatically when you open OE.

Now you will be able to receive messages normally again, but you will need a tool to get any messages you want out of the Inboxold.dbx file.

General precautions for Outlook Express:

Do not archive mail in the Inbox or Sent Items.  Create your own user defined folders and move the messages you wish to save to them. Empty Deleted Items folder daily. Although dbx files have a theoretical capacity of 2GB, I recommend about a 300MB max for less chance of corruption.

Information about the maximum file size of the .dbx files that are used by Outlook Express:
http://support.microsoft.com/?kbid=903095

After you are done, follow up by compacting your folders manually while working *offline* and do it often.

Click on Outlook Express at the top of the folder tree so no folders are open. Then: File | Work Offline (or double click Working Online in the Status Bar). File | Folder | Compact all folders. Don't touch anything until the compacting is completed.

Turn off e-mail scanning in your anti-virus program.  It is a redundant layer of protection that eats up CPUs and causes a multitude of problems such as time-outs and account setting changes. Your up-to-date A/V program will continue to protect you sufficiently. For more, see:
http://www.oehelp.com/OETips.aspx#3

And backup often.

Outlook Express Quick Backup (OEQB):
http://www.oehelp.com/OEBackup/Default.aspx 

Thanks Bruce I will follow your instructions to create a new inbox. On the question of data recovery, I have a second computer running on Windows XP with a larger inbox folder. If I export the old inbox from this computer to the newer one with the larger inbox folder, will I be able to read my messages, or is the inbox corrupted? And will I be able to export the inbox folder as it won't open at the moment?

Define 'larger Inbox folder'. The max size for any OE folder is 2GB period. That said, corruption often occurs long before that. Also, removing and deleting messages does not reduce the size until you compact.

If you exported the Inbox.dbx file to the other machine, it would still be corrupted. You can try this, but I doubt it will help.

Copy the corrupted Inbox.dbx file to the other computer's desktop and rename it. Don't try to import it into a folder currently in use. Import it into OE via these instructions.

How to restore individual dbx files
http://www.oehelp.com/backup.aspx#imp1 

Now, compact all your folders on this machine.

Click on Outlook Express at the top of the folder tree so no folders are open. Then: File | Work Offline (or double click Working Online in the Status Bar). File | Folder | Compact all folders. Don't touch anything until the compacting is completed.

Compact Your OE Folders:
http://www.insideoe.com/files/maintain.htm#compact 

If you can see the messages, good. But assuming you can't, you still have the old Inbox.dbx file on the original machine to run the tool on.