Security Certificate Error in Office 365

In this article, I discussed about error and resolution for "Security certificate Error" in Office 365. Generally, this type of error occurs when the certificate issued by a company is not trusted and Office 365 asks to view the certificate and to trust the certificate or not.

Error: "The security certificate was issued by a company you have not chosen to trust. View the certificate to determine whether you want to trust the certifying authority".

This type of error commonly occurs when you configure a Microsoft Exchange Online account (Office 365 account) in Outlook client application. You receive a security alert after you enter your account credentials.

Resolution:

To resolve this issue,we have to manually configure Outlook client with the following settings:

Log on to the Office 365 Outlook Web Access (OWA).

Inside of OWA, go to help/about.
Make a note of the first part of the "Host Name" entry (For example, SN1QRD0205) which is the server name and well as the first part of the external POP setting (ex. POD51004) which is the proxy name.

Log into Outlook and manually configure an Exchange connection with the following settings:

SERVER: the server name attached to .mailbox.outlook.com (ex.SN1QRD0205.mailbox.outlook.com)

CACHED MODE: Checked.

USER NAME: The full O365 email address of the account. Don't click "check name", click "more settings"

Go to the SECURITY tab.

Make sure the first box is checked, and security is set to "negotiate authentication"

Go to the CONNECTION tab.

Check "connect to Microsoft Exchange using HTTP" then click the "Exchange Proxy Settings" button

In the connection settings box, enter the proxy name attached to .outlook.com (ex. POD51008.outlook.com)

In the 2nd box enter msstd: outlook.com

All four checks should be selected

Under "Proxy Authentication Settings" make sure that "Basic Authentication" is checked.

If you follow the above procedure, error will be rectified.

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