How to setup AD sync with 2019 server and office 365 with a .local internal Domain

Hi,

technically, the steps are easy.
- Add the suffix for  all the messaging domains that you will use to authenticate (in the Domains and Trusts console)
- Change the userprincipalname of each users to set the main email address of the user.

ADSync cannot migrate your default domain ".local" but will migrate all these users using the new UPN.

If you keep the default domain for users, this domain will not be used by O365, and will be replaced by "@YourTenant.OnMicrosoft.com".

Deman is right. You can install Azure AD Connect on Windows 2019 and change the users UPN from .local to .com since if you do not change and sync users from syncing OU, these users will have a primary email set as "YourTenant.OnMicrosoft.com".

No issues with installing Azure AD Connect on Windows 2019 pretty straight forward.
1.You need to install using a static password user i.e. need a domain admin example administrator user.
2. Working O365 global admin credentials.

As Deman said you need to "Add the suffix for  all the messaging domains that you will use to authenticate (in the Domains and Trusts console)".

is there a way to change all the users in a custom OU with a powershell command to the new suffix.
And is there a way to put the .com as default so when we add a new user we don't have to change it every time. 

Yes, it is possible to address only one Organizational Unit. But it is probably better to update all users.
You can set a lot of users with a new Domain in UPN without doing script. If necessary, use "Saved queries".



No, the suffix domains cannot be set as default.
You must use script to create or update user as wanted, or change your creation process to select the correct domain in the suffix list proposed when you create a new user.

Thanks for all your help
The PowerShell command worked Great!!