From the articles in Google I know there is a risk if you upgrade your exchange server 2013 to CU6, in a environment coexistence with Exchange server 2007.
However we are in a Exchange server 2007 client environment, not server, all the office outlook clients in SCCM are still using Outlook 2007 client, expert please confirm if it is safe to install CU6 in such a environment like this, or what should I pay extra attention?
The upgrade is in a government environment so quite important to make sure everything goes right, basically we are in a DAG environment have Melbourne mailbox server, CAS server and Sydney mailbox server and CAS server as another pool.
The general steps I think is
1. prepare the AD schema update 3 days before doing the actual upgrade,
2. Put all 4 servers into maintenance mode one by one, MEL mailbox server --> MEL CAS server --> SYD mailbox server --> SYD CAS server.
3. Upgrade SYD mailbox server and CAS server first, reboot, take them out of maintenance mode, see if client can receive and send mail, all services is up.
4. If SYD pool works well, perform the upgrade in MEL mailbox and CAS as well.
5. Reboot and check if send receive mails are OK, all services are up and running, replication is fine, etc.
Anyone has experience please comment and please let me know if I miss any or should pay extra attention to which part?