Lion Mail: If Mail can’t verify message signatures
There can be several reasons why you receive a message with a banner at the top stating that Mail was unable to verify the message signature.
- The message was modified in transit. In this case, ask the sender to resend the message.
- The sender’s certificate may have expired. In this case, the sender needs to renew the certificate and then resend the message.
- You need to indicate that you trust the sender’s Secure/MIME (S/MIME) certificate.
- The email address on the S/MIME certificate doesn’t match the From address. This problem can occur if the addresses don’t use the same case or if a message is redirected. For case mismatches, the sender needs to change the From email address so that it exactly matches what is used on the sender’s S/MIME certificate. For redirected messages, the sender should not sign messages that they redirect.
To view detailed information about why the message signature could not be verified, click Show Details in the email banner.