how to Refuse to accept another domain's mail to local group

[shanghailxw@163.com]

HI,
I create a local group. i hope to accept local domain's mail，reject another domain's mail.
Can someone provide me the steps?
thank you advance.

[phoenix]

HI,
I create a local group. i hope to accept local domain's mail，reject another domain's mail.
Can someone provide me the steps?
thank you advance.

Mail is only accepted for the Domain that exists on the server and no others.