Cause: This problem occurs when the stream entries for the messages are inaccessible before Windows Mail deletes the messages from the Outbox

You cannot send or delete these messages. Every time that you close Windows Mail, you are prompted that there are unsent messages in your Outbox.

This articles helps to resolve problem where messages become stuck in the Outbox and cannot be deleted when using Windows Mail.

Follow the steps below to resolve the problem with Windows Mail.

Step 1
Microsoft confirms this problem with Windows Mail and has produced a patch for the same. Kindly download the patch and apply it. Click on the link to download the package.

After downloading the patch run it to install the package.

Resart the computer and try to delete the mail which was stuck in the Outbox.
Disclaimer The following methods include steps that directly copy or delete the file that is used by the Windows Mail application. If you change the file or folder by mistake, the message data may be erased. If that problem occurs, you must rebuild the message store or the Windows Mail folder.

Step 2: Rebuild the message store of Windows Mail

Click Start, and then type the location of messages into the Start Search box. To confirm the location of messages, follow these steps:
Start Windows Mail.
Click Tools, and then click Options.
In the Option dialog box, click the Advanced tab, and then click the Maintenance button.
In the Maintenance dialog box, click the Store Folder button.
In the Store Location dialog box, right-click Your personal message store is located in the following folder, and then click Select All.
When you select the strings, right-click Your personal message store is located in the following folder, and then click Copy.
Click Cancel or Close to close all the dialog boxes.
Close Windows Mail.

Right-click the Start Search box, and click Paste and then press ENTER.

In the opened folder, right-click the WindowsMail.MSMessageStore file, and then press DELETE.

Open the Backup folder and the New folder.

Press CTRL+A to select all files, and then press DELETE.

Close all folders.

Start Windows Mail to rebuild the message store database.
After you restart Windows Mail, the message store file is sucessfully repaired.

Note: If you receive the following error message, and the WindowsMail.MSMessageStore file cannot be deleted, start Windows Vista in safe mode and use Method 1 to delete the file: The action can't be completed because the file is open in another program. Close the file and try again.
Step 3: Rebuild Windows Mail folder

If rebuilding the database does not resolve the issue, follow these steps to rebuild the Windows Mail folder:

Close Windows Mail.

Confirm and copy Store Location of Windows Mail. To confirm Store Location, see Step 1 in “Method 1: Rebuild the message store of Windows Mail” that described above.

Click Start and paste the location path that found in Store Location of Windows Mail, place the cursor at the end of the pasted strings, and then press the Backspace key to delete the following strings.

Windows Mail
Notice that the default Windows Mail folder is located in C:\Users\username\AppData\Local\Microsoft\WindowsM ail

Press Enter and open the folder.

Right-click the Windows Mail folder, and then click Rename.

Input old at the end of the folder name and change the folder name as below
Windows Mailold

Start Windows Mail, confirm the Windows Mail folder is automatically created, and then close Windows Mail.

Note If new Windows Mail folder is compressed, you need to uncompress this folder.

Double-click the Windows Mailold folder used in Step 6 and open the folder.

Double-click Local Folder and copy the following file and paste the file into Local Folder in the new Windows Mail folder.

account{xxxxxxxxxxxxx}.oeaccount.

Note: xxxxxxxxxxxxx will be the numbers or alphabets.

If the following folders exist in the Windows Mailold folder, copy each folder into the new Windows Mail folder.

Stationery folder
Microsoft Community folder
Close all folders and import messages in Windows Mail. To import message, use the following steps:
Start Windows Mail.
Click File, point to Import, and then click Message.
Click Microsoft Windows Mail 7 in Select Program, and click Next.
Press Browse, select the location of Windows Mailold folder in Step 6, and then click Next
Click All folders in Select the folder, and click Next.
Click Complete, and then the messages will be imported to Imported Folder.

Save the messages in the previous Inbox that imported to Imported Folder in Local Folder. You can select to move any messages from Inbox to each folder.