Activation Mail Template
https://github.com/HDInnovations/UNI...vate.blade.php
You need to edit the values in the config/other.php via the config manager to set your site name and everything. UNIT3D is just default.
As for secure-headers. There exactly that. HTTP Secure Headers. Things like Content Security Policy, Referrer-Policy and more. Each is clearly defined in the config along with reference links so you can learn more about the options.
https://github.com/HDInnovations/UNI...re-headers.php