Issue
During the launch of Outlook Express, you receive the following error message:
An unknown error has occurred. Protocol: SMTP, Port: 0, Secure SSL: No, Error 0x800c0131
This problem may be due to an absence or corruption of
Folders.dbx file.
Solution
Restore the file
Folders.dbx.
Then locate the file Folders.dbx through the search tool of Windows
(Start / Search / Files or Folders).
Rename the file to make a backup, for example
Folders.back.
Launch Outlook Express.
Folders.dbx file will automatically be recreated and the application will open correctly.