security certificate revoked - outlook.office365.com

John Rovel Kalaw 6

The pictures below started popping up on our PCs. and the PC was using not part of any domain. I tried to follow the link below but the IE was inaccessible. https://answers.microsoft.com/en-us/outlook_com/forum/all/outlookoffice365com-security-certificate-has-been/743bdb2b-06ce-4206-923e-bdb7041528bd

Drifter 1 Reputation point

2022-10-08T18:50:23.963+00:00

I am not a computer person and also have this problem. I clicked into the Security Alert message's "View Certificate" button and saw that the certificate is issued to "outlook.com" while the security message said the internet address "outlook.office365.com" has security concern. That to me essentially is a Microsoft mess up by using Peter's credential to do business as Paul.

I think that I started to have this pop up issue around when the new certificate became effective, that was 7/25/2022.

As to some PCs/Macs don't have the issue maybe because they already have the correct security certificate installed on their computers. There is no setting in my hotmail setup for me to change in Outlook, so so far I am dealing with it by clicking ok on the box everyday.

49 answers

Limitless Technology 45,246 Reputation points

2022-07-29T11:05:05.153+00:00

Hi there,

As you have stated that you have not connected to any domain can you please check if you have updated with all patches and try disabling your firewall and see if you are getting this message?

There is some weird behavior in Outlook in connection with O365. Apparently, Outlook checks the validity of all your validated domains in your tenant but shows as error "outlook.office365.com cert revoked".

Have you verified that you can contact the CRL from within your network and that the certificate thumbprint of the cert you are getting the error with isn't in that list?

Hope this resolves your Query!

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Faery Fu-MSFT 19,896 Reputation points Moderator

2022-08-01T08:05:19.287+00:00

Hi @John Rovel Kalaw ,

Welcome to our forum!

Based on my experience there are some possible causes you can try to check on your side:

1.Proxies or firewalls.

2.MTU limits. Some reports also indicated it only happened on specific networks like WiFi or network provided by specific ISPs. It ended up with the root cause is MTU limits in these networks.

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A M 16 Reputation points

2022-09-19T18:23:34.19+00:00

Neither of these makes sense for certificate revocation because it's an explicit indicator that can't be triggered by a bad transmission, etc.

The referenced certificate is revoked, but at least one of Microsoft's servers hasn't been updated and now we are all risking that somebody may use the revoked certificate maliciously. It was revoked for a reason and most likely the certificate was compromised.
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Tim Cogley 6 Reputation points

2022-09-15T13:31:31.637+00:00

We are seeing the same cert warning.

Not everyone in our user base is seeing it (in fact, most are not)
All are AD systems, with the exception of the mobile devices
AZAD sync is active and syncing properly
Some laptops only see it on the wired network
Some laptops only see it on the wi-fi network
Some laptops see it on both networks
mobile devices on wi-fi
Some are seeing it again after clicking Ok.
All devices are current on patches and updates

All of this leads me to believe that it is not on our side.
We do need a solution.
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Daniel 1 Reputation point

2022-09-25T18:05:34.72+00:00

I also have recently started encountering this error message. I use Microsoft 365 through Outlook on my Windows computer, with the latest versions of Windows 10 and Office 365. The Exchange server is hosted by Microsoft.

If I click "OK" when the message pops up I can continue as before.

It would be good to understand what is causing this error message...
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Richard Tilley 1 Reputation point

2022-09-26T16:37:59.21+00:00

Apple Mail app on
Mac also gets this warning.
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security certificate revoked - outlook.office365.com

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