Thank you very much for implementing private key import for Proton accounts (https://protonmail.uservoice.com/forums/935538-accounts-payments/suggestions/10454982-import-priv).

I think it would be very useful to also have the option to import keys of non-Proton accounts. I use ProtonMail as my main account and forward all my work emails to my ProtonMail account, where I can apply all kinds of powerful filters to them. However, I receive a lot of PGP-encrypted emails on my work account and I am not able to decrypt them in the ProtonMail web interface. Even with the newly added private key import feature, I am not able to import the private key for my work email address, because I cannot add that email address to my ProtonMail account (as I do not own the domain of my work email address).

It would be useful to have the option to mark email address as "yours" (for emails that are forwarded from other accounts or emails that have been imported from previous non-Proton accounts). If one could then import the private keys for those accounts, it would solve this problem.