failed to Verify/Decrypt

[email protected] Tue, 26 Jun 2018 12:52:45 -0400
Newsgroups gmane.mail.mulberry.user
Message-ID <MTAwMDAxNi5jcm9w.1530032003@quikprotect>
Is that plug in outdated?  How do I update and install in Mulberry?

Even older signed emails now have the red warning.

Thank you,
Mu