“ ProtonMail Bridge is a desktop application that allows you to fully integrate your ProtonMail account with any IMAP and SMTP email client, including Outlook,

“ ProtonMail Bridge is a desktop application that allows you to fully integrate your ProtonMail account with any IMAP and SMTP email client, including Outlook, Thunderbird, or Apple Mail. Open sourcing the code lets anyone verify how the encryption process takes place through Bridge as the emails are transferred between your ProtonMail account and your desktop email app.”