At this time, Streak does not have an email encryption component or feature.
Our team's previous extension, Secure Mail for Gmail was deprecated on August 31st, 2018 to give way to Gmail's own solution for this secure mail: Confidential Mode.
The extension, if still installed, will advise you to uninstall it every time Gmail is launched in your browser. It will continue to decrypt mail that was sent or received with Secure Mail, but will not be able to encrypt any new mail.
Going forward, we recommend using Confidential Mode.