==== REQUIRED BASIC INFO OF YOUR IREDMAIL SERVER ====
- iRedMail version (check /etc/iredmail-release): 1.3.1
- Deployed with iRedMail Easy or the downloadable installer? downloadable installer
- Linux/BSD distribution name and version:  CentOS 8
- Store mail accounts in which backend (LDAP/MySQL/PGSQL):  LDAP
- Web server (Apache or Nginx): Nginx
- Manage mail accounts with iRedAdmin-Pro? No
- [IMPORTANT] Related original log or error message is required if you're experiencing an issue.
====

We have Exchange servers and iRedMail servers which are using the same mail domain, and there are mailboxes on both of them.
I would like the inbound mails are first sent to iRedMail, and if the recipient mailbox is on Exchange, then transfer the mail to Exchange.
Also I need users on both systems can send emails to each other.
I have read some discussions that mentioned configuring per-user transport, but I have configured iRedMail to integrate with Active Directory by following this article:
https://docs.iredmail.org/active.directory.html
so I don't know how to configure per-user transport.
I have read this article: https://gist.github.com/iredmail/fda90a … 18638e047, but it is for MySQL environment, I am using OpenLDAP and integrated with Active Directory, so I am not sure how to configure the cf files exactly?

Currently, Exchange users can send email to iRedMail users, but iRedMail cannot send email to Exchange users.

Another question, I want iRedMail Global Address Book can show all recipients that in both Exchange and iRedMail systems, how to do that?

Any help will be greatly appreciated.

Thanks,
Steven