Looking into mx3.mail.ovh.net? This is a subdomain of OVH, a widely used French hosting provider, and it's almost certainly part of their email server infrastructure. The domain itself isn't trying to impersonate anyone—the WHOIS records clearly list OVH as the owner and registrar. That legibility is a strong sign that you're not dealing with a fly‑by‑night operation.
That said, the subdomain is currently in a rough state. It loads a generic 503 error from OVH's load balancer, and there's no HTTPS available at all. For any kind of web‑based email access, you'd want a working, encrypted connection. This address isn't meant for direct consumer browsing; it's a backend server name. If you're trying to configure an email client, you'd use settings from OVH's main documentation, not this URL.
So is mx3.mail.ovh.net a scam? No. But is it usable right now? Also no. Until OVH gets the service running again and adds TLS, you should treat this subdomain as temporarily broken, not as a place to do anything important. There are no mx3.mail.ovh.net reviews because it's not a consumer product—it's infrastructure. If you stumbled here while checking your hosting config, hold off and verify with OVH support directly.