When I open Mail I receive a pop up - "Insecure update error! For security reasons, you need to sign your updates with a DSA key. See Sparkle's documentation for more information". I believe this is the result of me adding a new Plugin to Mail. I like the Plugin. How do I permanently remove this error message? I searched for information about Sparkle and I don't it is something I need, or want.
Sparkle is a software library used by many application developers as a means of distributing updates to their applications automatically over the Internet. However recently some security vulnerabilities where discovered in older versions of Sparkle.
See https://sparkle-project.org/documentation/security/
Some corporates IT departments may have taken steps to block/disable Sparkle as a brute-force means of 'fixing' this security issue.
Rather than relying on the vulnerable version of Sparkle to update your application or in this case plugin with presumably also a new fixed version of Sparkle you should check on the authors website and manually download and install a new fixed version.
Contact the maker of that Plugin to ask if there's an update coming. Only (s)he can solve this for you.
Insecure update error! DSA key. Sparkle
