We have a hybrid Exchange 2010 / Office 365 deployment and we are hoping to phase out the 2010 Server and replace it with Exchange 2013 CU11.

I have followed the prerequisite details found here (updated Schema/AD and installed relevant roles on new server) - https://technet.microsoft.com/en-us/library/bb691354(v=exchg.150).aspx 

So now I have a Server 2012 VM with Exchange 2013 CU11 installed with the CAS/Mailbox roles.

As we are phasing out the 2010 server, I assume the 2013 server will need a way to send out mail (similar to hub transport service in 2010), How do we do this?

Can we have two servers send mail concurrently? so we can test that the 2013 server works before taking down the 2010 server

As we are currently in a hybrid state with the 2010 server, we can only see the ~50 mailboxes that are hosted on premise (on the 2010 server) within the EAC on the 2013 server so we cannot manage the office 365 mailboxes from EAC.

Does this mean that we will need to re-run the hybrid tool? Can both servers be in a hybrid state at the same time?

I've tried to setup an outlook profile to connect to the 2013 server to access a mailbox hosted on the 2010 server however i get the error message 'The name cannot be resolved. the connection to microsoft exchange is unavailable. Outlook must be online or connected to complete this action'

I've tried to telnet on port 993 however the connection fails even though i've added an any any any rule in windows firewall on all three profiles.


That's a lot going on there.

  1. To aid you in future searches, you may find using the term "co-existence" a bit more helpful for mix version Exchange deployments. I would also start by reviewing the Exchange Deployment Assitant guides here: https://technet.microsoft.com/en-us/exdeploy2013/Checklist.aspx

  2. What you are doing is essentially upgrading Exchange environment to 2013. You need to be sure you setup the interfaces and load up the certificates just like you would if you added a 2010 server to your farm. Be particularly mindful of -- Autodiscover internal URI settings (this is the URL registered to the SCP so internal Outlook clients are directed correctly).

  3. You should run the Hybrid wizard if you want to use the 2013 server as the Hybrid server. That will update the connectors so mail between on-prem mailboxes and O365 flow thru that server.

  4. As far as which servers send "out" messages that is defined by your connectors. 2013 running both CAS/MBX roles has all the transport services running on them. If you are phasing out your 2010 server you want to be sure to create the proper connectors on the 2013 server. And if mailboxes will remain on-prem then you should migrate those to the 2013 server.

Make sure DNS is configured correctly for the server, and if you are going to use it as Hybrid server, use the connectivity analyzer to validate external settings.

  • Hello Jesus, Thanks for the advice. We are going to be at a point where no mailboxes reside on premise and are all in O365. The only mailboxes that are on premise at the moment are old leavers so all outlook clients are currently pointing to O365 (all MX records point to MS). This server is basically going to be a way to edit AD attributes of remote mailboxes and a relay for some printers/software that aren't O365 compatible to send mail to mailboxes in O365. OWA works on the 2013 server as i can access a mailbox hosted on the 2010 server, i'm not sure why outlook cant connect though – Z Holt Jun 3 '16 at 7:54
  • Also do you know why everybody's outlook client is now prompting a warning about the new servers self signed certificate? they are configured to point to O365. My theory is that O365 knows about out 2010 server via the hybrid, and now that the 2013 is part of the exchange group it must some how know – Z Holt Jun 3 '16 at 8:26

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