Outlook express

Which default directory, which Outlook Express?
For Outlook Express 5, you'll find all you need in the registry:
HKEY_CURRENT_USER\Identities\{some number}\Software\Microsoft\Outlook Express\5.0

In there you'll see the "Save Attachment Path" orthe "Store Root" (=where your mailfiles are).

Jim

Assuming you mean 'Mail Storage Folder' by 'default directory', you can change this folder to any folder of your choice.

Go to Tools-->Options--> Maintenance and then click 'Store Folder Button' and browse to the folder where you want to keep your mails.

Rohit