Outlook 365 - The server you are connected to is using a security certificate that cannot be verified

[markFoley]

I've just installed Office 365 on a new Windows 10 Pro computer in our office. Every time I start Outlook I get the message, "The server you are connected to is using a security certificate that cannot be verified. The target principal name is incorrect." The dialog has buttons to 'View Certificate', "Do you want to continue using this server? 'Yes' / 'No'. I click 'Yes' and Outlook comes up, but I have to click 'Yes' every time I start Outlook. Is there a way to NOT have this message come up?

I do understand why it's giving me this message. I have specified STARTTLS for the incoming server connection. The certificate is issues to the public domain name mail.mydom.org. Our mail server is self-hosted, IMAP. I have specified the incoming mail server as mail.dom.local, which, of course, doesn't match the certificate. I get it. However, I want all email to/from workstations to deal with the local Mail Submission Agent on our local mail server, and not get routed "outside" to the public domain.

I am using port 143 for incoming.

Outlook 2010, Thunderbird and Mac Mail all gave such a warning, but allowed the exception to be permanently stored so I didn't have to click the "'Yes' continue using this server" each time I started the email client.

How can I get this Security Warning to STOP popping up when I start Outlook?

Continue reading...