procmail implementation

[learnbash]

hello folks,

i have mail server with following details.

1.postfix(virtual domains]
2. courierimap


i have a domain example.com that have email accounts like.

user1@example.com
user2@example.com
user3@example.com
admin@example.com
staff@example.com[alias for user1@,user2@,user3@]

how i restrict that only admin@example.com have rights to send emails to staff@example.com. No one from outside and no one from inside will not sent email to staff@example.com only admin@example.com will sent email to staff@example.com. Please suggest how can i achieve that.

Edit/Delete Message

[falko]

I think you can achieve this with Postfix header_checks. http://www.postfix.org/header_checks.5.html