You can also use the following steps to quickly see which emails have notes while you are still in your Inbox (or any other folder).
The EmailNotes column will display Yes if the email has any notes.
Right-Click on your column header (the section showing your fields, From, Subject above) and Select Customize Current View&
(In Outlook 2010 Select the View Tab and click Add columns)
Click the Fields& button on the form that appears.
Select User-defined fields in folder from the drop-down box .
Select EmailNotes from the Available fields list and click Add.
Note: If EmailNotes does not appear in the list of user-defined fields then click Cancel and Add a Note to any email in the folder first.
You can change the order of this field by clicking on the Move Up and Move Down buttons.
Click OK to save .
You will now be able to see the EmailNotes field in the folder.