In order to allow autodiscover to work without changing the DNS records back to the Giacom platform we can add an entry to the Hosts file on a computer that will point the autodiscover to the right location. Instructions on how to do this are below.

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1. C:\Windows\System32\drivers\etc
1. Edit "hosts" as an admin
2. Add a new line to the bottom:
a. {IP} {HostName}
b. Example:
i. 51.140.253.155 autodiscover.domain.com


Collect the Needed IP with the below:
1. CMD
2. NSLOOKUP
3. Autodiscover.GiacomCP.com
Copy one of the two IPs that is then listed
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Once this change has been made to the Hosts file you should be able to configure an Outlook profile for the Hosted Exchange mailbox. However, if this fails you may need to make some changes to the registry using the below reg keys to allow Outlook to search for none Microsoft 365 based mailboxes.

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Please open regedit and go to:

HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\AutoDiscover

Please create the following 32 bit DWORDs with a value of 1

ExcludeExplicitO365Endpoint

ExcludeHttpsAutoDiscoverDomain

ExcludeHttpsRootDomain
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Once these reg keys have been entered, please relaunch Outlook and create a new profile in Outlook, this should then allow you to configure the Hosted Exchange mailbox within Outlook so that you can create the PST backup.

I would recommend changing the reg key values to 0 once you have completed the mailbox PST extraction to ensure this does not cause any mailbox issues on the local computer in the future when trying to configure a Microsoft 365 mailbox.