Hi,

We've recently migrated our on-premise Exchange to Office 365 but we keep management of users in our on-premise Active directory and dirsynced the attribute changes to Office 365. As per Microsoft recommendation, an Exchange server with CAS and Mailbox role should still be on-premise to manage the Exchange attributes. I have two Exchange 2013 servers, one CAS and one Mailbox, I wanted to decommission the Mailbox role server so that I can reuse the storage.

Is it possible to uninstall the Mailbox role and then add the role in the existing Exchange CAS server?

Or, I'll just uninstall Exchange on the 2 servers and setup a new Exchange server with both CAS and Mailbox role?

I suggest you first install mailbox role on the CAS server and uninstall the standalone mailbox server.

Ensure you make the settings similar to the first Mailbox server.

Hi,

Thanks will try this. Will let you know.

Hi,

When you say "make the settings similar to the first Mailbox server", does it mean I need to create the same database (name and size) on the new server as with the standalone mailbox server?

The idea is I need to decommission the standalone mailbox server to recover the space used by the databases. Is it possible to install the mailbox role in the existing CAS and start with a fresh database and then uninstall the standalone mailbox server?