Secure communication code for notifications

Wise came up with a great idea to reduce phishing: Their customers can setup a secure communication code in the UI that will be included in all communications from Wise.

Proposal

Let our users set up such a code that will be used in communications from GitLab. This code should also be exposed as a header so users can create gmail filters based on it for example (and set a kind of legit label if needed).

To improve the UX over the Wise experience, it would be nice to have a way to auto-generate the code in the UI.