Hello support team ,

We are planning to deploy Exchange 2013  "Exchange 2010/2013 Coexistence"

Just wondering Will there be any disruption of our internal/external email delivery for the OWA Outlook 2010 user access  during Exc2013 installation and config ?

We utilize OWA internal / external access and Outlook anywhere has been enabled on exchange 2010.

I just want to make sure our internal/external email on the Exchange 2010 server works, until Exchange 2013 is fully tested ,configured and all user mailboxes  have been migrated across.

I understand that Exchange 2010/2013 Coexistence will need to point all Clients access to the Exc2013 CAS server.

Thank you

The one thing I would say is to make sure you install the certificate as soon as you can (or stop IIS) otherwise Exchange 2013 will become an response point for Autodiscover requests.  If the cert/name is invalid they will receive a cert prompt.

Another option would be to install Exchange 2013 on it's own AD Site, and then move it to the production site once all testing has been completed.

As suggested by Hinte install certificate on CAS servers as soon as you finish exchange2013.

Plan upgrade on a weekend. Install Exchange2013 and move 2 mailboxes to Exchange2013. Add host entries common-name/namespace/autodiscover. in your PC to point to Exchange2013.

Test your mailbox by sending emails to yourself and a user in Exchange2013,user in Exchange2010 and vice-versa.

Try to download address book. Test active sync using activesync software from your PC. Test POP and IMAP if using.

If all working well move the remaining mailboxes and change the A records to point to Exchange2013 and change the NAT in your firewall to Exchange2013.

Hi MAS and Hinted ,

Just to clarify ....

we want to Install exchange 2013 in the current AD Site and have it working in coexistence with Exchange 2010 while all resources are migrated across

Currently mail ,autodiscover DNS and NAT firewall are all pointing to the Exchange2010.

In case of installing Exchange 2013 I don't understand reason behind, Outlook clients receiving certificate errors if they mailbox is still on the Exchange 2010 and all DNS record are pointing to the Exc 2010 .

Could you please explain ... 

Thank you for your help.

For example if your exchange2010 not reachable to clients it will try to reach the next available CAS server which is Exchange2013. And if there is no certificate configured you will have certificate error.

Please check this to get the command to create CSR
http://gallery.technet.microsoft.com/Exchange-20072010-and-2013-17a0b52f

Please check this to install certificate.
http://exchangeserverpro.com/exchange-2013-complete-pending-certificate-request/

FYI CAS is the client int

By the way, when planning to deploy Exchange 2013 in coexistence scenario, following Exchange server deployment assistant would be a good approach that covers all the required steps for swing migration.

Moreover, this available automated solution(http://www.exchangemigrationtool.com/) could also be a good alternative solution while need to migrate users mailboxes from Exchange 2910 to 2013.

Hi Mas,

I was planning to export wildcard cert from the current Exc 2010 and import it to the Exc 2013

Would that be OK ?

Thank you 

You can use a wildcard cert, although it is recommended that you use a SAN cert.  

https://technet.microsoft.com/en-us/library/dd351044%28v=exchg.150%29.aspx?f=255&MSPPError=-2147217396

The other thing I would say, is that for Exchange 2013 to respond to Autodiscover requests Exchange 2010 does not have to be done.  Basically Outlook internally does a SCP lookup for Autodiscover endpoints for the AD Site the User is currently in. DNS will respond with the AutodiscoverURL for one of the CAS Servers in that site.  It could be a 2010 CAS server or it could be an Exchange 2013 server.  If it's a 2013 server they will receive a cert warning if the Exchange 2013 does not have a valid cert.

Hi

Sure you can have Coexistence of Exchange 2010 / 2013 without any issues, and more over we need to know your current Exchange Topology like how is your Email Gateways configured and how is your HT servers configured etc. to give you more details, but any how keep your Email Gateways at the end of migration.

For more information go through the below link, which will help you more.

http://msexchangeguru.com/2013/05/10/exchange2013-migration/comment-page-13/ 

regards,

MB Shaikh.

Hi Milan,

Hinte and MAS are correct.

@Hinte

For a time being Before mailbox migration and certificate installation on 2013 server can we overcome this issue by having all the scp points with the same name as mentioned  below .Then we can have the Host A record for "autodiscover.sundaramfinance.in" to resolve only to the ip address of the exchange 2010 CAS servers .

https://autodiscover.sundaramfinance.in/Autodiscover/Autodiscover.xml

So on such case if the outlook takes the scp point which belongs to exchange 2013 cas server then it will get resolved in to anyone of the exchange 2010 cas server and it will not go to the exchange 2013 CAS which doesn't have the SAN certificate installed.

Hi Milan,

Hinte and MAS are correct.

@Hinte

For a time being Before mailbox migration and certificate installation on 2013 server can we overcome this issue by having all the scp points with the same name as mentioned  below .Then we can have the Host A record for "autodiscover.sundaramfinance.in" to resolve only to the ip address of the exchange 2010 CAS servers .

https://autodiscover.sundaramfinance.in/Autodiscover/Autodiscover.xml

So on such case if the outlook takes the scp point which belongs to exchange 2013 cas server then it will get resolved in to anyone of the exchange 2010 cas server and it will not go to the exchange 2013 CAS which doesn't have the SAN certificate inst