My client runs 2 companies, lets call them X and Y. They have their own office 365 setups, so accounts from company Y are treated as external users by X's SharePoint sites. I would have to grant access to every account separately.
Is it possible to automatically allow users with a specific domain to access one of the sites?
If you have enrolled in the SharePoint and OneDrive integration with Azure AD B2B, you may set domain restrictions, more detailed informtion, please refer to "Allow or block invitations to B2B users from specific organizations" and "External sharing overview".
For individual file sharing in SharePoint Online, please refer to "Restrict sharing of SharePoint and OneDrive content by domain".
