If you are unable to delete the message while in offline mode or cannot go into offline mode, you'll need to change your default delivery location.
Note that this option should be rarely needed – if you are patient and wait a few minutes for Outlook to stop the message spooler, or close Outlook and restart it in offline mode, in almost all cases, the stuck message will delete without issue.
Change the Default Delivery Location
- Outlook 2010: Open File, Account Settings dialog
Outlook 2007: Go to Tools, Account settings
- Select Data Files tab (1) then click Add (2). Create a new PST for your profile then select it and click the Set as Default link (3).
- Close Outlook then restart it.
- Show the folder list, using Ctrl+6 if necessary, and find the old Outbox. Delete the message.
- Repeat steps 1, 2, and 3, restoring the original pst as the default delivery location.
- Show the folder list and move any new messages from the new pst to the original pst.
- Right click on the new folder's name and Choose Close to remove it from your profile.
Last updated on December 17, 2015.