[qmailtoaster] Create domain internal & external in 1 server

[Firdaus Tjahyadi]

Dear All

we have 2 domain in our mail server

1. dic.com (external)
2. internal.dic.com (internal)

that's run well, now i want to restrict email account from internal ( [EMAIL PROTECTED]) only send to internal ([EMAIL PROTECTED]) too, that cannot send to other domain (internet)

how to setup that kind rule ?
what file i must edit to make that rule ?

thanks for any help

regards