Question
Can I leave spam email in my email account INBOX?
Answer
Yes.
The "SpamBox" feature work alongside the "Spam Filter" feature.
cPanel: Home -> Email -> Spam Filters
Option: Move New Spam to a Separate Folder (Spam Box) (Can be enabled or disabled)
Enabled: marked email goes to the "spam" folder
Disabled: marked email stays in the "INBOX"
From inside the cPanel account, leaving "SpamBox" off will put the marked spam email in the INBOX.
To enable "SpamBox" for use server-wide, enable it in Tweak Settings.
WHM: Home -> Server Configuration -> Tweak Settings
Enable Apache SpamAssassin™ Spam Box delivery for messages marked as spam (user configurable) (Turn on here)
The "SpamBox" feature is enabled by default.