Exchange 2019/outlook 2016

[alacard052003]

Hello all. We have three exchange servers in different domains but they all fall under the same site(AD site and services) Our DC's for the three domains also follow that topology. I think this impossible but I would like to ask the room. How do i get a outlook client in domain 1 to use the exchange in domain 1 and sof forth. When I open up outlook and show connection status I see connections from exchange servers in the different domains. like the SMTP is the correct domain but the in the server name column I have a few connections like https://mail.domain1.com  https://mail.domain2.com and mail.domain3.com all established and connected. Without managing sites and services is there another way match the connection from client in outlook to the domain? I read about send and receive connectors but not sure if this would alleviate the problem. All ideas are welcome as i have been trying to figure this out

[#2]

Outlook client connections on domain joined machines connected to the internal network generally use the SCP record for autodiscover queries, and autodiscover provides the connection URLs the Outlook client uses. You should be able to control access by making sure the SCP record in each domain points to a DNS name that directs the connection to the correct Exchange server and that Exchange server returns the appropriate connection URLs that in turn point to the correct Exchange servers.

If your mailboxes have permissions to mailboxes in other domains, you may see connections to mailbox servers in other domains for that access.

[#3]

So when I do the autodiscover test from client and look at the log from it behaves as expcected ie.
Attempting URL https://autodisover.domain.com/autodiscover/autodiscover.xml found through SCP
Autodiscover to https://autodisover.domain.com/autodiscover/autodiscover.xml starting
GetLastError=0, httpStatus=401
GetLastError=0, httpStatus=200
Autodiscover to https://autodisover.domain.com/autodiscover/autodiscover.xml Succeded.

When I go to mailbox delegation the only thing that has full access to the mailbox are exchange servers and exchange trusted subsystem would these groups be causing my issue

[#4]

And the URLs are correct that autodiscover returns?
What about the connection status? Which URLs are used for each connection?
What abut DNS...Are all DNS names pointing to the correct location, and if you have load balancing is that redirecting to the correct namespace
It's more about what this mailbox has delegate access to (connection status might show the details of this)

[#5]

Thanks for the reply. So the urls are correct for autodiscover. No issues connecting to a mailbox upon first time mail setup. When first time setup happens it points to the right server. If you close out of outlook and open it back up it will find another exchange server and connect to the mailbox. We have a parent domain and three child domains. No exchange in the parent domain but one exchange server in each of the child domains. The behavior happens with any mailbox. I only want the mailboxes to connect to its respective domain and not search for the first available exchange server it can find.

[#6]

Forgot to mention we dont have load balancing.