In April, we released an update to the Management tools in Exchange Server 2019 that enables organizations that use Azure AD Connect and sync their Active Directory to manage Exchange recipients with...
Updated Aug 15, 2023
Version 7.0
Blog Post
Nino_Bilic
Microsoft
MicrosoftSteveTH We never said (as far as I know) that it is recommended to install Edge into a domain; in fact, exactly the opposite:
...Because the Edge Transport server is installed in the perimeter network, it's never a member of your organization's internal Active Directory forest and doesn't have access to Active Directory information. However, the Edge Transport server requires data that resides in Active Directory: for example, connector information for mail flow and recipient information for antispam recipient lookup tasks. This data is synchronized to the Edge Transport server by the Microsoft Exchange EdgeSync service (EdgeSync)...
Edge Transport servers | Microsoft Learn
...We recommend that you install Edge Transport servers in a perimeter network that's outside of your organization's internal Active Directory forest. Installing the Edge Transport server role on domain-joined computers only enables domain management of Windows features and settings. Edge Transport servers don't directly access Active Directory. Instead, they use Active Directory Lightweight Directory Services (AD LDS) to store configuration and recipient information. For more information about the Edge Transport role, see Edge Transport servers...
Install Exchange Edge Transport servers using the Setup wizard | Microsoft Learn