This is much needed! Struggling to make payments currently using a credit card due to browser blocking it !!!

1) Login with Ethereum wallet (Metamask..)
2) Send mail to any eth address
See https://ethmail.cc/

BTC LTC NMC PPC ETH DOGE RDD XMR etc. PPC and Eth can be excluded. but the possibility to register .bit domains with proton can resolve the situation about anonymity.

Improvement to deposit funds in the account (or can be a revolution) and letting the possibility to begin a new manner of bank stocking. So, To integrate until 12 wallets for crypto currencies with the possibility of the owner to have the private keys of wallets. More details if interested.

I think protonmail hosting an in app crypto currency wallet would be a huge win. People already trust protonmail to store communication why not expand the platform to include crypto currency wallets?

+Dogecoins!

In today's world there is a big problem of bitcoin storage. ProtonMail has established itself as a reliable service. You are already accepting bitcoins for payment. But that's not enough. Let's make it possible for users to store bitcoins on their wallets. From these purses they will be able to pay for the services of ProtonMail and transfer to other places, at their discretion. It was very comfortable and would add a lot of protonmail stars. You would have had a great commercial success because you are reliable and honest people.

Look at this - https://gemini.com/security/

I like your security model so I would like to store my bitcoins here....offline storage etc... thanks

Eager to see Protonmail Team consider creating a Crytocurreny Wallet for users to store and exchange cryptocurrency with the likes of Bitcoin, Etherieum etc