How to Fix Outlook Error: “Outlook is unable to connect to the proxy server”

Outlook error code 8: “Outlook is unable to connect to the proxy server”

Description: the error message is triggered when you are trying to send or receive emails from Outlook, through a proxy server. The regular reasons are:

    • Your Windows root certificates are outdated
      Solution: open Windows Update and look for updates to the Root Certificates list. Mark these updates and install them.
    • You are using a self-signed certificate
      Solution: by default, a self-signed certificate is added to the Intermediate Certification Authorities. You have remove it from there, then import it to the Trusted Authorities list.

Here is a step by step tutorial on how to add a Certificate to Windows.