Seperating mail users to different mail server

==== Required information ====
- iRedMail version: 0.8.6
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): LDAP
- Linux/BSD distribution name and version: Centos 6
- Related log if you're reporting an issue:
====

Hi Zhang,

We received a requirement from a client. He wants 30 users to be migrated to google apps. & Rest of the users in iredmail users.

They have configured in google apps saying if user's doesn't exists in google apps forward the mail to iredmail server. Vice versa is not working.

In iredmail server It says unknow user or user doesn't exists..

Waiting for your earlier reply

Thanks