accessing non-account INBOX possible with IMAP?

I'm trying to get imapfilter (linux program) to be able to access the
INBOX that doesn't have any account attached to it.
This INBOX receives all the email that is not sent specifically to an
account that have a username and password.

The cpanel default address 'catch-all' can
send all non-account addressed email to any email address OR simply
fail/bounce the emails. This has been left blank so that no email received fails or bounces.


Is there a way to access this 'no account set for it' INBOX?
Going into webmal in cpanel and using say, horde.
Down the left side menu there is:

INBOX (no specific email account - all unrouted email arrives here)
account1 (has username and password)
account2 (has username and password)

'account1' and 'account2' have email accounts that have been created
with a username and password via cpanel yet the INBOX does not.
Ideally it would be possible to access this no specific account set INBOX without
altering the Default address field. The Default address being left
blank.

You'll see this INBOX when you go into cpanel webmail

imapfilter program is able to move and delete etc. emails, though finding out if
and how to access the INBOX that does not username and password is necessary
to use imapfilter on it.