Exchange 2013 CU1 and Co-Existence

Last night (2nd April) the Exchange team finally released the Exchange 2013 Cumulative Update 1 (CU1) patch that we have been waiting for to permit co-existence with previous versions of Exchange. (

I’ve had a very quick look at this today in my lab environment to see what Exchange 2013 Co-existence looks like out the box.

The first job was to update my Lab Exchange 2010 server to SP3 (required for co-existence) – straightforward enough though it does, as expected, require downtime of Exchange Services to apply the Service Pack, and SP3 also includes an AD Schema update too, so – full backup of AD first!  FYI SP3 is a slipstreamed install and now supports Server 2012.

Next I created a new Server 2012 VM and joined it to my Lab domain. The only pre-requisites, other than Server 2012 Roles & Features, are the Microsoft Unified Communications Managed API 4.0 Runtime ( and the Office 2010 64Bit FilterPack SP1 (

Now I could run the downloaded CU1 Exchange-x64.exe file to unpack the installation files and run Setup.exe.

The Exchange 2013 CU1 installation now runs through with an option to install all required Roles and Features on the server, very helpful other then requiring a re-boot to complete the install, before then needing to re-running setup.exe to actually start the install.

The install itself is, as expected, very straightforward with the only real option being which role or roles to install (Only CAS or Mailbox roles now in 2013).

Once installed the fun starts – as Exchange 2013 no longer has the Exchange Management Console all administration is via the web based “Exchange Control Panel”. This is great but, at this point my Administrator mailbox still resides on the Exchange 2010 server so when I login to the 2013 URL my session is proxied to 2010, presenting me with the 2010 ECP and no knowledge of the Exchange 2013 world!

A quick check of TechNet and I find this:-

If your mailbox
exists on an Exchange 2010 Mailbox server, the Exchange 2010 ECP will
automatically load in your browser. This is by design. You can access the EAC
by adding the Exchange version to the URL. For example, to access the EAC whose
virtual directory is hosted on the Client Access server CAS01-NA, use the
following URL:

So now I can connect to the 2013 ECP and see all my 2010 objects I test moving a mailbox from my 2010 server – this all works as expected by creating a “New Migration Batch” which even sends me a mail when complete. I can login to the mailbox using OWA and get the new clean, modern interface to send a test mail.

The mail sends to mailboxes on 2010 and I can reply back to 2013 successfully  – job done!

I’ll play with this lab more over the coming weeks and if I find anything of interest I’ll let you know.



2 responses to “Exchange 2013 CU1 and Co-Existence

  1. Hi,

    Great article!

    Were you able to connect to an Exchange 2013 mailbox database using an Outlook client?

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