Reception of mail from a corporate box

There is centos7, in it CWP7. Updates are made. With the help of CWP and hands postfix is configured.
One user and under it the mass of VMAIL for the domain.
Postfix accepts on smtp mail from the outside and decomposes on boxes.
Internal clients send mail to the Internet and to local neighbors.

Problem: there is still a corporate box for this domain at provider. Letters get to it too.
It is necessary to force postfix to accept periodically on letter POP3 from this box, to decompose it in local vmail, and then to devastate a corporate box.
How to make it? Tell me please, most in detail as I am a beginner in CENTOS7 and in POSTFIX

Yury