Your messages are scored in two ways:
1. Automatically as they are received in one of your Incoming Folders.
2. Manually by using the Score icon on the CleanOut ribbon, where you have the option to Score:
- Selected E-mail(s) - which is/are the emails you have selected in your Inbox or other Incoming Folder
- New E-mail(s) - which are all unscored emails in the last two weeks
- All E-mail(s) - which means all emails in your Incoming Folder
(The Quick Score check box tells CleanOut not to look inside the email body or text which makes it a lot faster)
When you start CleanOut for the first time you are encouraged to just score the New E-Mail(s). From that point forward all of your new emails will be scored automatically unless you notice that a message or messages did not get scored for some reason, in which case you can click on the Score icon to do it manually.
When you have time, though, it is a good idea to score all emails so that you can use the date range filter to see older messages. Note that this might take a while if you have a lot of messages in your Inbox (say > 10,000) so you may want to do this over lunch or while you will be in a meeting as your PC will be tied up for this time. If you have a slow Internet connection, you may also put Outlook in offline mode, by clicking on Send/Receive->Work Offline, to make it go faster.