Migration Halted - Working external OWA address doesn't match EMC configured external OWA address

I'm progressing through an Exchange 2010 to Exchange 2016 Migration with co-existence. I'm to the point where I need to Update Virtual Directory URL's and Domain DNS records and have stumbled upon a question I need answered before I'm comfortable proceeding.

Our users access OWA externally with, for example:

External - - https://email.domain.com/owa (Currently working External Access)

However, within the EMC and also through power shell commands I'm shown the current OWA external address and its different. For example I'm shown:

External - - https://webmail.domain.com/owa ("Configured" - non working External Access )

I am unable to find the currently working external address of https://email.domain.com/owa anywhere within my exchange or IIS environment. Where I do find it referenced is in my SSL Exchange certificate and in a MX record. What am I missing on the exchange side? How does Exchange now that https://email.domain.com/owa exisits and is a portal for access? Where is this configured such that I can't seem to reference it?

Assistance is appreciated.
Dave SchaferDirector of ITAsked:
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Valentina PerezExchange ServersCommented:
Hi Dave,

When you run the command in Exchange 2016:

Get-OwaVirtualDirectory | fl *url*,server

Do you receive in both the same url?

timgreen7077Exchange EngineerCommented:
if you are in co-existence with 2010 and 2016 and if https://webmail.domain.com/owa is the virtual directory you have for OWA, you will need to make sure that webmail.domain.com is a name on your SSL cert, and you also need to create an external DNS A record pointing webmail.domain.com to your Internet facing Exchange 2016 server or whatever your inbound gateway is but pointing to Exchange 2016. Exchange 2016 will proxy the connection to the 2010 Mailbox for users still on 2010 and of course user on 2016.
Dave SchaferDirector of ITAuthor Commented:
To answer both of you:

Valentina, I do not have the same external OWA address in 2010 and 2016 at the moment.

Tim, your information is helpful to ensure I have the appropriate split DNS in place for co-existence. Will the current email.domain.com/owa being utilized no longer be accessible after I make changes,  and access be reliant upon whatever is configured in 2016? Sounds like any users with mobile phones or tablets will be screwed until provided with the new settings.

However, my question as to why the current usable external OWA address is different than what is configured in exchange, and where that current usable OWA address is configured is yet a concern of mine. I understand that in the grand scheme of the migration it may not be relevant or prevent my progress. Knowing I can likely continue without issue is great, but in regards to understanding and knowledge I would very much like to know why there is a conflict between the configuration and what is actually working.

The clue I have is in a prior migration a legacy host name was created in conjunction with GoDaddy where are records are hosted.
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timgreen7077Exchange EngineerCommented:
Since you are in co-existence exchange 2016 will proxy connections between your 2010 and 2016 mailboxes, so your current URL isn't needed. Since you currently dont have external DNS pointing to the new URL for 2016 that is why those users can't access OWA externally. Owa has nothing to do with mobile phones and tablets when connecting to email unless you are using OWA on those mobile devices to access email, but they user activesync for mobile email. This change will only affect OWA. If you have an extra external IP your can have 1 IP pointing to the exchange 2010 servers for OWA and have the 2nd IP pointing to Exchange 2016 for OWA so you can test and make sure that your 2010 users can access OWA via the exchange 2016 URL. We are currently running in co-existence and all users access OWA via the 2016 URL. If your co-existence setup is fine, then you should have no problems with that.

As to why the setup are different is depends on who setup and confirgured your environments, but you can see the confirg for both exchange setups but running the following:

Get-OWAVirtualDirectory -Server servername | ft InternalURL, ExternalURL

If you wanted to change the URL you can run:

Get-OWAVirtualDirectory -Server servername | Set-OWAVirtualDirectory –InternalURL "email.domain.com/owa" -ExternalURL "email.domain.com/owa"

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Dave SchaferDirector of ITAuthor Commented:
I appreciate your clarification. I would really like to know where the "legacy" settings are coming from, but I'll press on.

I've had no issue configuring Exchange 2016 with updated OWA settings. DNS and A records were a breeze and OWA is working fine internally and externally.

Thank you again for the assistance.
timgreen7077Exchange EngineerCommented:
good luck and take care.
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