There are 2 different S/MIME error codes that can show up in the emails you receive from Penneo.
Problem 1
Error message:
This message has a digital signature, but it was not verified because your browser or platform currently does not support the S/MIME control element.
Solution:
See this guide to turn on S/MIME: Microsoft help enter guide
Problem 2
Error message:
The digital signature on this message isn't valid or trusted
Solution:
This error code doesn't concern the digital signatures in any signed case files that might be attached to the email.
This is related to Outlook or other email clients when they do not recognize the certificate we use to sign emails from penneo@penneo.com