Apple Mail Unable To Verify Message Signature: What to do


If you use Apple Mail and receive an email with the error message “unable to verify message signature,” it means that the message was signed with a digital certificate that Apple Mail doesn’t recognize or trust. This can happen for various reasons, such as an expired certificate or an incorrectly configured certificate. In any case, you need to take some actions to ensure the message is safe and secure.

In this article, we will discuss what to do when you receive an email with an unverified signature and how to take precautions to prevent security issues.

  1. Verify the Sender and Email Address

The first thing you should do when you receive an email with an unverified signature is to verify the sender and the email address. This is important because the signature is intended to verify the authenticity of the sender’s digital identity. If you don’t recognize the sender, or if the email address looks suspicious, you should not open the email.

Here are some steps you can take to verify the sender and the email address:

  • Check the sender’s name and email address carefully to ensure they are genuine.
  • Check the email address in the header of the email to ensure it matches the sender’s name and the email address in the “from” field.
  • If the email is from a company, check the domain name to make sure it is legitimate.

If you’re unsure about the sender or the email address, you should not open the email or click on any links or attachments within it.

  1. Verify the Digital Certificate

If you trust the sender and are confident that the email is legitimate, you can try to verify the digital certificate that was used to sign the message. To do this, you will need to obtain a copy of the digital certificate and import it into your keychain.

Here are the steps to verify the digital certificate:

  • Ask the sender to provide you with the digital certificate they used to sign the email. They should be able to email it to you or provide a link to download it.
  • Open Keychain Access, which is located in the Utilities folder within the Applications folder.
  • Choose File > Import Items, then select the digital certificate file.
  • Enter the password for the certificate, if prompted.
  • Select the certificate in the Keychain Access window, then choose File > Get Info.
  • Expand the Trust section and set the “When using this certificate” option to “Always Trust.”

Once you have imported the digital certificate, try opening the email again. If the email was signed using the imported certificate and the certificate was valid, you should no longer see the “unable to verify message signature” error message.

  1. Disable Signature Verification

If you’re unable to verify the digital certificate, or if you don’t want to go through the process of importing it into your keychain, you can disable signature verification in Apple Mail. This will allow you to open the email, but it will also remove the security benefits of message signing.

Here are the steps to disable signature verification:

  • Open Apple Mail and go to Mail > Preferences.
  • Click on the “Accounts” tab and select the account that is experiencing the issue.
  • Click on the “Security” tab.
  • Uncheck the box next to “Verify signatures.”
  • Close the preferences window.

After you have disabled signature verification, try opening the email again. If the email was signed using an unrecognized digital certificate, you should now be able to open it without seeing the “unable to verify message signature” error message.

  1. Ask the Sender to Resend the Email

If you’re still unable to verify the signature or the digital certificate, it’s best to contact the sender and ask them to resend the email. This time, they can sign the email using a recognized digital certificate, or they can send the email without a signature.

  1. Check your email account settings

Sometimes, issues with verifying email signatures can arise due to incorrect email account settings. It’s important to ensure that your email account settings are configured properly.

Here are some things you can check:

  • SMTP settings: Ensure that your SMTP settings are correct. SMTP is the protocol used to send email messages, and incorrect settings can cause issues with email signatures.
  • SSL settings: Secure Sockets Layer (SSL) is a protocol used to secure email communication. Ensure that your SSL settings are enabled.
  • Ports: Check that the correct ports are being used for incoming and outgoing email traffic. Incorrect port settings can cause issues with email signature verification.

To check your email account settings on Apple Mail:

  1. Open Apple Mail and go to the Mail menu.
  2. Click on Preferences.
  3. Select the Accounts tab.
  4. Select your email account from the list on the left-hand side.
  5. Ensure that your account settings are correct. You may need to refer to your email provider’s documentation to ensure that you have the correct settings.
  6. Save any changes you make.
  7. Update your Apple Mail application

If all else fails, updating your Apple Mail application may help resolve issues with verifying email signatures. Sometimes, older versions of Apple Mail may have bugs or compatibility issues that can cause problems with email signature verification.

To update your Apple Mail application:

  1. Open the App Store on your Mac.
  2. Go to the Updates tab.
  3. If there is an update available for Apple Mail, click on the Update button next to it.
  4. Wait for the update to download and install.
  5. Restart Apple Mail.

If the issue persists after updating Apple Mail, you may need to contact Apple Support for further assistance.


In summary, being unable to verify a message signature on Apple Mail can be frustrating, but it’s usually not a cause for concern. It simply means that the email’s signature cannot be verified by Apple Mail for various reasons, including expired or untrusted certificates, incorrect email account settings, or bugs in the Apple Mail application.

If you encounter this issue, there are several steps you can take to try and resolve it, including checking your certificates, adjusting your email account settings, and updating your Apple Mail application. If the issue persists, you may need to seek further assistance from Apple Support or your email provider.