Hi,

In the middle of migration from one exchange 2010 server to 2013 server and thought things were going well.  However migrated mailboxes to exchange 2013 are not accessible through outlook although they are through OWA most of the time.

I ran test connectivity comandlet on 2013 server on mailboxes and they tested okay.

However when you connect to mailbox it says exchange unavailable.  

I have a new ucc certificate on the exchange 2013 server that includes mail.contoso.com and autodiscover.contoso.com.  These are both setup to point to 2013 server with split brain dns.  The 2010 server has a certificate for mail.contoso.com.

The SC for autodiscovery right now for both the exchange 2010 and 2013 servers are https://mail.contoso.com/autodiscover/autodiscover.xml

When I run outlook connectivity test I get the following failure: 

Test Steps
Attempting to ping the MAPI Address Book endpoint with identity: exg:6004.
The attempt to ping the endpoint failed

Additional Details

The RPC_S_SERVER_UNAVAILABLE error (0x6ba) was thrown by the RPC Runtime process.
Elapsed Time: 24085 ms

Test Steps   Attempting to ping the MAPI Address Book endpoint with identity: exg:6004.   The attempt to ping the endpoint failed.    <label for="testSelectWizard_ctl12_ctl06_ctl00_ctl07_ctl00_tmmArrow">Tell me more about this issue and how to resolve it</label>   Additional Details   The RPC_S_SERVER_UNAVAILABLE error (0x6ba) was thrown by the RPC Runtime process. Elapsed Time: 24085 ms

Hi

Did you migrate your DNS to point to the new Exchange 2013 Server?