Thanks ZhangHuangbin. Can you advice me on this scenario: I have an e-mail account that is supposed to receive and save a copy of mails/messages, this e-mail account should have members that will need to send e-mails using a different identity and those who will not be able to send any email with this identity email but they should only receive a copy of emails in their mailbox. Where should I place members with permission to receive a copy and send email using this identity and where should I place members that will only receive a copy?

Maybe here's the general solution:

*) Remove 'reject_sender_login_mismatch' in /etc/postfix/main.cf.
*) Enable plugin 'reject_sender_login_mismatch' in iRedAPD. Sample setting in its config file /opt/iredapd/settings.py:

plugins = ['reject_null_sender', 'amavisd_wblist', 'reject_sender_login_mismatch', ...]

# List all local senders who are allowed to send as different identities
ALLOWED_LOGIN_MISMATCH_SENDERS = ['user1@xx', 'user2@xx', 'user3@xx']

# Don't strictly restrict sender identities to user alias addresses.
ALLOWED_LOGIN_MISMATCH_STRICTLY = False

With below settings, only 3 users (on your server) listed in ALLOWED_LOGIN_MISMATCH_SENDERS are allowed to send email as different identities. WARNING: it can be any identities.

*) For "those who will not be able to send any email with this identity email but they should only receive a copy of emails in their mailbox", you can forward email to them.

I am using OpenLDAP as backend to store accounts and iRedAdmin to manage users.