Mozilla Thunderbird is one of the most popular email clients that can manage multiple email accounts under a single platform. The ProtonMail settings include the IMAP/POP and SMTP server settings that can be configured in the Thunderbird client. ProtonMail provides a Bridge application to seamlessly encrypt and decrypt your emails as it enters and leaves your computer. Before configuring Thunderbird to use your ProtonMail email account, download and install the Bridge application on your computer. For detailed instructions to configure Thunderbird Protonmail settings, follow these steps.