sarajo,

By default all sent items are supposed to stay in the Sent items folder. If you are experiencing sent items moved to a secondary folder in the Inbox, then its possible a rule was created to do so.

Since you have stated that no rule has been created, was a rule created to perform this action before? This also could be a server side rule that was implimented after a data import.

Try performing this Outlook 2007 command switch:

To run Outlook with a command line switch, use the following steps:

Windows XP:

• Click Start.
• Click Run.
• Enter the following in the Run dialog box (with quotations):
  "c:\program files\microsoft office\office12\Outlook.exe" //cleanclientrules
• Click OK.

Starts Outlook and deletes all client-based rules.

The following switch will clean both client and server side rules:

/cleanclientrules

Hope this helps