Outlook The Security Certificate Was Issued By A Company You Have Not Chosen To Trust 【FAST ◆】

Never click "Yes" to this error on a public network. Always verify the "Issued by" field. When in doubt, call your IT helpdesk and ask, "Did you guys recently roll out a new internal root CA?"

It sits there, staring back at you, blocking your calendar, your email flow, and your sanity. Do you click "Yes," "No," or "View Certificate"? And more importantly, should you be worried? Never click "Yes" to this error on a public network

Decoding the Outlook Nightmare: "The Security Certificate Was Issued by a Company You Have Not Chosen to Trust" Do you click "Yes," "No," or "View Certificate"

Stay secure. Stay skeptical. And for the love of all that is holy, stop using self-signed certificates for production Exchange servers. Stay skeptical

Your company uses Microsoft Exchange Server on-premise. The server presents a self-signed certificate or one issued by your internal Microsoft PKI (Certificate Services). Your personal computer doesn't know your company's internal CA. Outlook sees "Issued by: Contoso-Internal-CA" and thinks, "I don't know Contoso. I never agreed to trust them."

Let’s cut through the noise. This isn't just a random glitch; it’s a critical security mechanism waving a red flag. Here is a deep dive into what causes this error, the genuine risks involved, and the surgical steps to fix it—without compromising your network security. First, understand what Outlook isn’t saying. It is not saying the connection is unencrypted. It is saying, "I have a valid mathematical lock, but I don’t recognize the locksmith who made it."