Mail Says Unable to Verify Message Signature
Reading Time: 2 minutes When using the Mail app on your Mac to read or compose emails, you may see a notice saying, “Unable to verify message signature. The digital signature for this message is incorrect. The message may have been tampered with or corrupted since being signed by youremail@account.” You may also see a message saying, “Mail was unable to verify the authenticity of the S/MIME certificate provided by [email protected].”
This may occur because the mail you are reading is signed with a certificate your Mac does not recognize. It is possible that the sender’s certificate may not be valid or may be expired. This issue may also occur when you are trying to send an email with attachments. In fact, I was having this issue when trying to send emails with PDF attachments. And lastly, this issue may occur because the S/MIME certificate doesn’t match the “From” address.
If you are having this issue while sending emails, you can turn off the signature. In the compose view, you will see the signature option, as I show in the screenshot below. Click the drop-down menu and select None. This will stop generating certificates.
If you are having this issue with an email you have received, you can try to trust its certificate. Follow these steps:
- In the error message, click Show Certificate.
- If you trust it, review it first, then select “Always trust the certificate.”
- Click OK.
If your issue continues, delete the mail account (in Mail, go to Mail > Settings > Accounts > Remove), and then re-add the account.
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