We have a brand new setup of Exchange 2016 and Outlook 2016 (or in my case, Office 365 version of Outlook 2016 client). The computer is a Windows 10 system, and is joined to our 'new' domain that we'll be using to replace the 'old' domain. It has a different set of domain controllers, a completely different domain namespace, etc.

We have autodiscover working (through some DNS hackery to use a different DNS server to make our system's autodiscover point to the new Exchange environment and not the older Exch 2010 we have on the older environment), and the domain controller integration setup and working with the Exchange server. The computer running Windows 10 is joined to the same domain as Exchange 2016 is. However, when we try and connect Outlook 2016 to the Exchange account, we get this message and error:

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When we disable cached exchange mode manually in the Exchange account settings via Control Panel > Mail, we get a different message:

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Now, this all being said, if we set up the profile manually for Exchange ActiveSync service via Control Panel > Mail > Account Settings > Email > New, we get the behavior that Exchange when it tries to authenticate can't login as the user:

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I'm a little lost as to how we would enable Exchange access with Outlook in this case. Anyone got any ideas as to why this behavior would be this way?

  • We have autodiscover working through some DNS hackery...Please provide some detail on what you did. Assuming a default Active Directory and Exchange install, this is almost certainly your problem. – Twisty Impersonator Nov 1 '18 at 20:52
  • @TwistyImpersonator We have a small overlap with the problem. The DNS Hackery is that we have a DNS server that serves autodiscover.domain.tld to the actual proper Exchange server. The IP ranges and subnets for our current exchange server (and email domain) are shared with the 'new domain', so DOMAIN\username and NEWDOMAIN\username are different individuals. Are you saying that attempting to do two domains in the same IP ranges could cause this issue? (pg.sub.domain.tld and pgh.domain.local are the less-scrubbed full 'domains' here) – Thomas Ward Nov 1 '18 at 21:50
  • Note that domain.tld is a publicly-addressed domain, for relevance here. – Thomas Ward Nov 1 '18 at 22:01
  • yes, I suspect autodiscover is the problem, though if that's the case, your question would do better on Server Fault. If you agree I suggest you edit your question to provide more details about how you have autodiscover configured and we can migrate the question to that site. – Twisty Impersonator Nov 1 '18 at 22:07
  • It looks like the client is trying to connect to the old exchange server, but it belongs to a different domain so it cannot authenticate. So you have both exchange servers on the same wire and in the same subnet but in different domains? I would move the new machines to a different subnet just to keep the old and new from accidently talking to each other. Also, does the new DNS have a MX record pointing to EXCH2016? Just thinking out loud here... – Larryc Nov 2 '18 at 22:00

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