1. Uninstall the anti-virus
  2. Backup the *.dbx file
  3. Working offline (File -> tick Work Offline)
  4. Perform a manual compact (File -> Folder -> Compact)
  5. Close Outlook Express
  6. Find and Rename “outbox.dbx”, ”sent.dbx”, “folder.dbx”…….. Open CMD, then type dir *.dbx /s to find the exact location of the file.
  7. Try to open OE and send email again. It should regenerate new “outbox.dbx”, ”sent.dbx”, “folder.dbx”