I would like to propose an optional safety feature (opt-in) for the Proton Mail web app and desktop client: a user-defined Action PIN required before sensitive actions are performed, such as:

• Sending an email
• Permanently deleting emails (or emptying the Trash)
• Accessing the contact list

Why this is useful:
If a user temporarily leaves their computer unlocked in an office, shared space, internet cafe, or public area, anyone who walks by can currently send emails, permanently delete them, or access the contact list. An optional PIN would serve as a vital last line of defense against unauthorized physical access.

How it could work:
1. Opt-in Switch: Fully optional in Settings -> Security & Privacy, so it doesn't add friction for users who don't need it.
2. Customizable Actions: Users can choose which actions require a PIN (e.g., only Permanent Delete, or both Send & Delete).
3. Easy Reset: If the PIN is forgotten, it can be reset immediately by authenticating with the account password or 2FA.

This would be a great addition to physical security and user control for the Desktop/Web ecosystem!