Outlook custom toolbars are saved here

Microsoft Outlook stores toolbar information, including any custom toolbars you create, in a file named outcmd.dat. You’ll find this file in the following folder:

C:\Documents and Settings\username\Application Data\Microsoft\Outlook

C:\Users\username\AppData\Roaming\Microsoft\Outlook

It’s a good idea to back up this file after you customize the interface. If something goes wrong, you can reclaim missing toolbars by replacing the current copy of outcmd.dat with the backup. You can also use this file to copy custom toolbars to another instance of Outlook.

Windows hides outcmd.dat by default. To view it so you can copy or replace it, you must enable Show Hidden Files And Folders in Windows Explorer by choosing Folder Options from the Tools menu and then clicking the View tab.