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How to Resolve “Invalid Certificate” Error When Sending Emails in Outlook?

Anonymous
2024-09-03T14:31:13+00:00

I’m encountering an issue when sending emails from my Outlook.com account. Every time I try to send a new email, I receive the following error message:

Invalid Certificate - Microsoft Outlook cannot sign or encrypt this message because you have no certificates which can be used to send from your email address. System Information:

  • Outlook Version: Version 2408 (Build 17928.20114 Click-to-Run)
  • Operating System: Windows 10

Steps I’ve Already Tried:

  1. Verified that the security settings are set to <Automatic>.
  2. Found a workaround by manually selecting the email address from the From button, which allows the email to be sent without the error.
  3. Checked that other secondary accounts do not have this issue, possibly due to lower security level certificates.

Additional Information:

  • The issue seems specific to the default email account (two others I use in Outlook do not have this issue).
  • Other accounts do not require a password entry for each session.

What I’m Looking For:

  • A solution to configure Outlook so that I don’t need to manually select the account each time.
  • Any insights into why this issue might be occurring specifically for this account.

Thank you for your help!

***moved from Microsoft 365 and Office / Other / For home / Other***

Outlook | Windows | Classic Outlook for Windows | 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.

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  1. Anonymous
    2024-09-04T06:35:25+00:00

    Dear Bleak Morn,

    Thank you for posting in the Microsoft community.

    I understand that you encountered an error when sending emails using a certain account, and I'd be delighted to assist you.

    Regarding this issue, first, please navigate to File -> Options -> Trust Center -> Trust Center Settings… -> Email Security, and ensure that the checkboxes for "Encrypt contents and attachments for outgoing messages" and "Add digital signatures to outgoing messages" are both unchecked.

    Additionally, if you're using this account to send signed or encrypted emails, please ensure that this account has obtained a certificate and that it has been properly configured on your Outlook client.

    Here's a possible reference link for that：Secure messages by using a digital signature - Microsoft Support

    We appreciate you spend your time working on this issue. Feel free to post back if you need further assistance.  I wish you all the best.

    Best Regards,

    Ulrica.W - MSFT | Microsoft Community Support Specialist

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  2. Anonymous
    2024-09-08T07:18:14+00:00

    Dear Bleak Morn,

    Reconfiguring accounts is a regular way to troubleshoot errors.

    I will provide you with screenshots to guide you through the reconfiguration process. Since the configuration methods may vary depending on the type of account, may I first ask what is the issue email suffix you are using? And what configuration protocol (Exchange/IMAP/POP) are you using?

    You can check the protocol by clicking on the "File" menu, selecting "Info", and then scrolling down to the "Accounts" section. Please see the screenshot below for reference:

    Best Regards,

    Ulrica.W - MSFT | Microsoft Community Support Specialist

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  3. Anonymous
    2024-09-08T02:46:12+00:00

    Have you tried reconfiguring this default account?

    Can you be more specific?

    Yes, I have reported the issue with the Feedback feature in Outlook.

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  4. Anonymous
    2024-09-06T08:40:12+00:00

    Dear Bleak Morn,

    Thank you for your reply.

    It's indeed strange that the account can function normally after selecting it again from the drop-down list, which doesn't seem to be a problem that can be solved through specific settings. Have you tried reconfiguring this default account?

    Also, I suggest you click "Help" - "Feedback" in the Outlook menu bar to report this issue to Microsoft. Thank you for your patience.

    Best Regards,

    Ulrica.W - MSFT | Microsoft Community Support Specialist

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  5. Anonymous
    2024-09-05T17:23:03+00:00

    Dear Ulrica,

    Thank you for your assistance. However, adding digital signatures to outgoing messages is the desired configuration for my account. Unchecking the checkbox would prevent it from working as intended.

    The certificate is properly configured, as it works correctly after selecting the address a second time from the “From” drop-down menu. Additionally, I have two other accounts with certificates from the same provider, and they automatically select the account when chosen in the “From” drop-down.

    Only the default email account is experiencing this issue, and only before interacting with the “From” drop-down. This seems to be a bug in this version of Outlook.

    Thank you for your help.

    Best regards,
    Mark

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