Almost, but not quite. Emails sent between Proton accounts are demonstrably and reliably encrypted using the same technology your bank would to protect private information. We can even set them to self destruct at a later date and time. Emails sent to me from another address (gmail, AOL, HotMail) will only be safe from my side, and our entire conversation is at risk the minute it leaves my mailbox. Consider signing up for a free ProtonMail account now, and continue to use it with me or any time you think you need some extra caution.