When using Outlook with MS Exchange, you can open another user’s mailbox (providing that they have assigned permissions correctly). This is useful if you want to check whether a colleague is available..or you just want to snoop at an ex-colleague’s whereabouts!

However, Outlook remembers the names of the previous few users whose mailboxes you have opened (Click File > Open do display the list) – handy if you want to check the same user’s calendar again but could also land you in trouble if you’ve been snooping!

To clear the list:

Quit Outlook and start the Registry Editor (START > run > Regedit)

Locate the 101e0390 value under the following key in the registry:

HKEY_Current_UserSoftwareMicrosoftWindows NTCurrentVersionWindows Messaging SubsystemProfilesa0d020000000000c000000000000046

Click the 101e0390 value in the right pane of the Registry Editor.

On the Registry menu, click Export Registry File. Browse to the drive and folder where you want to store the export, type MRURegKey in the File name box, and then click OK.

After you export the file, right-click the 101e0390 key, and then click Delete.

Quit Registry Editor

OR if that key is missing:

Locate the 101e0384 value under the following key in the registry:

HKEY_CURRENT_USERSoftwareMicrosoftWindowsNTCurrentVersionWindows Messaging SubsystemProfiles\user_profilea0d020000000000c000000000000046101e0384