As I understand it, Proton Drive uses the encryption key of the default email address in your Proton account to keep your drive volume end-to-end encrypted. From my perspective as a user, this poses a significant design issue, as it presents several problems:

• You cannot accept invitations to collaborate on folders or documents sent to an email that isn't the original email address used to encrypt your drive. The invitation will still appear in the Proton Drive app as pending, but you won't ever be able to accept it. Therefore, collaboration is no longer privacy-friendly, as you may need to expose your primary email to people you don't want to share it with.

• There isn't a way to change the address associated with Proton Drive; the only solution offered by Proton's support is to wipe your volume and recreate it with a new address. However, this would require you to download all the content first and then re-upload it to the new volume.

• The email address you used to create your Drive account is exposed, even in files shared with a public link. You don't have the option to hide your email when sharing files or choose an alias instead, defeating the mission of Proton.

The email address of the Proton Drive account should be configurable and not default to the account's email, allowing the user to change the email address when needed. Until this is solved, Proton Drive is a broken solution for most advanced users seeking private and collaborative cloud storage.

For example, one user may start using Proton with a default address using one of the Proton domains (example@proton.me) and later decide to change it to use their own domain (example@example.com). This user won't be able to use Proton Drive normally anymore after switching their emails.