I have a similar system set up for my kids accounts.  I have a few email addresses whitelisted and the rest of the emails get redirected to a folder called UNSAFE.  I check their accounts via IMAP and move any emails I want them to be able to see by moving the emails from the unsafe folder to the INBOX.  When they check their email accounts via POP they get only the emails in their inbox.  Filters are set as follows:

RULES
----------
From - does not contain - first whitelisted email address
AND
From - does not contain - second whitelisted email address
AND
From - does not contain - third whitelisted email address

ACTIONS
-------------
Deliver to Folder - /.unsafe

you could also redirect emails to  null and have the automatically deleted.  It's not a difficult process to set up.