ClamXav Preferences

[Danny]

I am using 2.0.5 version of ClamXav
I need to set up the Sentry in the preferences to scan emails when they arrive in the in-box.
I see the + and - symbol. I know to click on the + ,I am not sure what to do as the next window appears to open and lists my applications.

How do I select the in-box of the Mail application.



.