If you've landed on highdorn-my.sharepoint.com, you're looking at a SharePoint Online site hosted by Microsoft. These subdomains are commonly used by organizations for internal document sharing and collaboration. The site immediately redirects to Microsoft's official login page, which is exactly what a legitimate SharePoint tenant should do.
There are no red flags in the underlying infrastructure: the site has a valid SSL certificate, enforces HTTPS, and is protected against clickjacking. It's not on any blacklists, and Google's Safe Browsing gives it a clean slate. That said, the specific organization using this tenant isn't publicly visible, which is normal for this type of service but means you can't independently verify the tenant owner from the domain alone.
If you're an employee or member of the organization that set up this SharePoint, you can confidently log in knowing the technical protections are in place. If you're a visitor who doesn't recognize the site, treat it like any other Microsoft login prompt — verify the redirect URI starts with login.microsoftonline.com before entering credentials. There's no evidence this site is a scam or fake; it behaves exactly as a legitimate SharePoint Online tenant does.