Share via

Outlook root certificate not trusted when using Office 2016 for Mac with Office 365

Anonymous
2015-11-26T02:10:46+00:00

Hello,

I am running into an issue when connecting to our Office 365 Exchange service. I am using the latest version of Outlook on Mac, and my operating system is OS X El Capitan 10.11.1. When opening Outlook, I am presented with a Verify Certificate dialog with the following message:

"A secure connection cannot be established with the server xxx because its intermediate or root certificate cannot be found. Do you want to continue? If you continue, the information that you view and send will be encrypted, but will not be secure."

The name of the root certificate authority is completely different to our domain. When expanding the dialog, I am clearly shown that this root certificate is not trusted. My options are to always trust this root certificate authority, to cancel, or to continue. 

It appears this is a known issue, but I am not comfortable with always trusting this root certificate authority. Why is this happening? Hitting cancel returns me to Outlook, yet strangely my emails are synchronised successfully.

Many thanks!

Outlook | MacOS | Legacy Outlook for Mac | For business

Locked Question. This question was migrated from the Microsoft Support Community. You can vote on whether it's helpful, but you can't add comments or replies or follow the question.

0 comments

Answer accepted by question author

Anonymous
2015-12-01T07:09:48+00:00

Thanks for the reply. I finally managed to get behind why this is happening. Microsoft Support pointed me to this article: 

https://support.microsoft.com/en-us/kb/3066652

Autodiscover works slightly different in Outlook for Mac compared to Outlook for Windows. My problem was that our website is hosted elsewhere, and the SSL certificate presented does not point to our particular domain name but rather the generic hosting domain name. This discrepancy causes the issue I was seeing. To resolve it, either trust the certificate (with no impact to security), or, reissue a valid certificate for our domain name. 

Again, thanks for all the replies, and assistance.

Was this answer helpful?

3 people found this answer helpful.
0 comments

3 additional answers

Sort by: Most helpful
Most helpful Newest Oldest
  1. Anonymous
    2015-11-28T17:31:23+00:00

    This issue should have been addressed in a later update for Outlook 2016 for Mac. Are you running the most current 15.16 version?

    I still see this, however, I’m hosting three domains on my one Office 365 account. I only see these certificate messages for my secondary domains not my primary.

    Was this answer helpful?

    0 comments
  2. Anonymous
    2015-11-26T21:30:21+00:00

    Thanks for the reply. Unfortunately this didn't work. I am still presented with the same problem.

    Any other ideas?

    Thanks!

    Was this answer helpful?

    0 comments
  3. Anonymous
    2015-11-26T18:50:44+00:00

    Was this answer helpful?

    0 comments