security certificate revoked - outlook.office365.com

John Rovel Kalaw 6 Reputation points
2022-07-27T04:28:49.213+00:00

Hi

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

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Outlook Management
Outlook Management
Outlook: A family of Microsoft email and calendar products.Management: The act or process of organizing, handling, directing or controlling something.
4,897 questions
Windows Server Security
Windows Server Security
Windows Server: A family of Microsoft server operating systems that support enterprise-level management, data storage, applications, and communications.Security: The precautions taken to guard against crime, attack, sabotage, espionage, or another threat.
1,724 questions

49 answers

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  1. Limitless Technology 43,941 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!

    ---

    --If the reply is helpful, please Upvote and Accept it as an answer–

    2 people found this answer helpful.
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  2. Faery Fu-MSFT 17,011 Reputation points Microsoft Vendor
    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.

    If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".
    Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.

    2 people found this answer helpful.
  3. 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.

    1 person found this answer helpful.
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  4. 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...

    0 comments
  5. Richard Tilley 1 Reputation point
    2022-09-26T16:37:59.21+00:00

    Apple Mail app on
    Mac also gets this warning.

    0 comments