This article demonstrates how to install a certificate from an Inky user (including yourself). This will enable you to trust the sender when you receive signed mail from Inky, and you or your recipient wish to install that Inky certificate and read the mail without the warning on a non-Inky client.

1. If an Inky user (who you recognize - or even for yourself) sends you a digitally signed mail from Inky for the first time, there will be a banner at the top of the mail "Unable to verify message signature".

2. Selecting "Show Details" --> "Show Certificate" reveals the full path of the Inky Certificate Authority (CA) Root in the upper display window. Apple will warn you that they are still unable to verify the message signature (that's OK, you are about to override this).

3. If you want Inky to trust this sender, click on the "Trust" arrow. In the top menu, "When using this certificate", change the "Use System Defaults" to "Always Trust". This will automatically change the other two menu options ("Secure Mail (S/MIME) and "x.509 Basic Policy") to "Always Trust". Click "OK" to confirm.

5. After you click "OK", your Mac will prompt you to enter your machine username and password.  (It does this because you are making changes to your "Certificate Trust Settings".) When you have entered the necessary information, select "Update Settings".

You're all set! Now you're connected with this sender and trust their digital signature.  This ensures that mail from that address is only from that sender.