Open Source Swift Email Clients

Thunderbird iOS is the official iPhone and iPad email client offering from the Thunderbird project, bringing the capabilities of a feature-rich, open-source email experience to iOS devices with native UI and Apple platform integrations. The app gives users a powerful tool for managing multiple email accounts, including IMAP and POP3 configurations, and supports modern authentication flows like OAuth for popular providers. Designed with mobile usability in mind, it includes familiar gestures, thread views, swipe actions, attachment previews, and integrated search so users can stay productive on the go. It also handles common email needs like organizing with folders, setting flags, and filtering messages, while respecting platform norms for notifications, background fetch, and data usage. By maintaining a connection to the desktop Thunderbird project’s ethos, the iOS client places emphasis on transparency, extensibility, and user control.

Proton Mail for iOS is the official iPhone and iPad client that brings Proton’s secure, end-to-end encrypted email service to Apple’s mobile ecosystem, combining strong privacy protections with native performance and gestures. The app allows users to sign in to one or multiple Proton Mail accounts, read and compose encrypted messages, schedule emails, protect emails with passwords, set expiration timers, and organize mail with labels and folders inside a smooth, intuitive iOS interface. It makes use of Apple’s networking APIs and encryption frameworks to deliver seamless management of encrypted communications while respecting platform conventions like touch navigation, Apple notifications, and background refresh. All sensitive operations — including key handling and encryption — occur locally on the user’s device, ensuring that plaintext messages and secret keys are never exposed to Proton’s servers or third parties.