I would like to suggest a security feature for Proton accounts: the ability to disable login for secondary email addresses.

Currently, additional Proton addresses associated with the same account can also be used to sign in. It would be useful to have an option for each secondary address such as:

“Allow this address to be used for login: On / Off”

This would allow users to keep their primary Proton address private and use secondary addresses publicly for email communication without increasing the number of identifiers that can be used to access the account.

The secondary address should continue to work normally for sending and receiving emails, but it should not be accepted as a login identifier when this option is disabled.

This would improve account security by reducing the attack surface, especially for users who want to keep their main login address confidential.

Ideally, this setting could be managed individually for each Proton address under Identity and Addresses.

Thank you for considering this feature.