Welcome to the forums! I'm not 100% on what your asking. However WHM's 'Host Access Control'
provides the ability to allow or deny clients' access, based on the IP address, to the following services:
POP3 (Courier or Dovecot)
IMAP service (Courier or Dovecot)
Official cPanel Documentation for Host Access Control can be found here: cPanel Docs - HAC
Of course, if you need assistance you can always open a ticket with the Support Department as well.