Share via

How to clear "The digital signature on this message can't be verified", this only happens on one of my laptops

Paul Cooper 20 Reputation points
2025-06-26T12:26:29.5233333+00:00

I have a crazy situation.

One of my suppliers sends me emails with content that is stripped or removed with a reported digital signature verification error.

This only happens on the laptop where I tried to resolve the problem by installing the S/MIME extension. Other laptops give a warning, but allow me see the content, my phone is ok too.

So now I have to forward emails from my phone to my laptop from this one domain.

I cannot work out how to fix this, please advise.

Microsoft Edge | Microsoft Edge development

Answer accepted by question author

  1. Damien Pham (WICLOUD CORPORATION) 1,755 Reputation points Microsoft External Staff Moderator
    2025-07-04T04:10:28.55+00:00

    Hello Paul,

    Thank you for your patience

    You can try the following instruction to remove the S/MIME extension:

    1. Remove the S/MIME Extension from Outlook Web

    Unfortunately, OWA doesn’t have a simple “uninstall” button for S/MIME once it’s enabled. But you can:

    • Go to Outlook Web Settings → Mail → S/MIME.
    • Uncheck “Encrypt contents and attachments for outgoing messages” and “Add a digital signature to outgoing messages.”
    • If that doesn’t help, try accessing OWA in Incognito/Private mode or a different browser to bypass the extension.

    If the extension was installed via a browser plugin (e.g., Edge or Chrome), you can disable or remove it from the browser’s extension settings.

    1. Clear Browser Cache and S/MIME Settings

    Sometimes the S/MIME config is cached in the browser:

    • Clear cookies and cache for outlook.office365.com.
    • Restart the browser and log in again.
    • Try accessing the email again.

    If the solutions do not work, I suggest you reach out to Microsoft by opening a support ticket for further and more affective assistant.

    Was this answer helpful?

    0 comments

1 additional answer

Sort by: Most helpful
Most helpful Newest Oldest
  1. Paul Cooper 20 Reputation points
    2025-09-30T07:13:38.8033333+00:00

    From Damian on support,

    "Access OWA in Incognito/Private mode or a different browser to bypass the extension"

    • this is an excellent recommendation

    Clearing S/MIME extension from OWA is quite tricky, Damian further recommended this method. I have not had time to test it yet.

    1. Remove the S/MIME Extension from Outlook Web

    Unfortunately, OWA doesn’t have a simple “uninstall” button for S/MIME once it’s enabled. But you can:

    • Go to Outlook Web Settings → Mail → S/MIME.
    • Uncheck “Encrypt contents and attachments for outgoing messages” and “Add a digital signature to outgoing messages.”
    • If that doesn’t help, try accessing OWA in Incognito/Private mode or a different browser to bypass the extension.

    If the extension was installed via a browser plugin (e.g., Edge or Chrome), you can disable or remove it from the browser’s extension settings.

    1. Clear Browser Cache and S/MIME Settings

    Sometimes the S/MIME config is cached in the browser:

    • Clear cookies and cache for outlook.office365.com.
    • Restart the browser and log in again.
    • Try accessing the email again.
    • Remove the S/MIME Extension from Outlook Web

    Unfortunately, OWA doesn’t have a simple “uninstall” button for S/MIME once it’s enabled. But you can:

    • Go to Outlook Web Settings → Mail → S/MIME.
      • Uncheck “Encrypt contents and attachments for outgoing messages” and “Add a digital signature to outgoing messages.”
        • If that doesn’t help, try accessing OWA in Incognito/Private mode or a different browser to bypass the extension.

    If the extension was installed via a browser plugin (e.g., Edge or Chrome), you can disable or remove it from the browser’s extension settings.

     1. **Clear Browser Cache and S/MIME Settings**

    Sometimes the S/MIME config is cached in the browser:

    • Clear cookies and cache for outlook.office365.com.
    • Restart the browser and log in again.
    • Try accessing the email again.

    Was this answer helpful?

    0 comments

Your answer

Answers can be marked as 'Accepted' by the question author and 'Recommended' by moderators, which helps users know the answer solved the author's problem.