: To save a single message, sign in to the web app at mail.proton.me, open the email, and use the Export or Download option to save it as an .eml file.
Once you've downloaded and installed ProtonMail, you're ready to start using the service. Here are some tips to get you started: protonmail download
Search for “ProtonMail” in your respective app store. Download and install. Upon first launch, you will either sign in or create an account. The app will then synchronize your encrypted mailbox. The entire download size is typically under 100 MB. : To save a single message, sign in to the web app at mail