Pros of Tutanota

• Open-source client and server, allowing for full code audits
• Supports end-to-end encryption for emails, contacts, and calendars
• Uses a unique encryption method that allows searching encrypted data

Cons of Tutanota

• Smaller user base and community compared to Proton Mail
• Limited third-party integrations and add-ons
• Less frequent updates and feature releases

Code Comparison

Tutanota (JavaScript):

crypto.pbkdf2(passphrase, salt, iterations, keyLength, 'sha256', (err, derivedKey) => {
  if (err) throw err;
  console.log(derivedKey.toString('hex'));
});

Proton Mail (Kotlin):

val derivedKey = PBKDF2WithHmacSHA256.deriveKey(
    password = passphrase.toByteArray(),
    salt = salt,
    iterations = iterations,
    keyLength = keyLength
)
println(derivedKey.toHex())

Both projects implement secure key derivation functions, with Tutanota using Node.js crypto module and Proton Mail using a custom Kotlin implementation. Tutanota's approach is more standard and widely used, while Proton Mail's implementation may offer more control over the process.

Pros of Delta Chat

• Decentralized architecture using existing email infrastructure
• Open-source and community-driven development
• End-to-end encryption by default

Cons of Delta Chat

• Less polished user interface compared to Proton Mail
• Smaller user base and ecosystem
• Limited advanced features like custom domains or bridge support

Code Comparison

Delta Chat (Kotlin):

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main)
    setupNavigation()
}

Proton Mail (Java):

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    initializeViews();
}

Both projects use similar Android development practices, but Delta Chat is primarily written in Kotlin, while Proton Mail uses Java. Delta Chat's codebase tends to be more concise due to Kotlin's features, while Proton Mail's Java code is more verbose but potentially more familiar to traditional Android developers.

Delta Chat focuses on simplicity and decentralization, making it appealing for privacy-conscious users who prefer open-source solutions. Proton Mail offers a more polished experience with additional features, catering to users who prioritize a comprehensive email service with strong security measures.

Pros of FairEmail

• Open-source and privacy-focused, allowing users to audit the code
• Supports multiple email providers, not limited to a single ecosystem
• Highly customizable with numerous features and settings

Cons of FairEmail

• Less polished user interface compared to Proton Mail
• Steeper learning curve due to extensive customization options
• May lack some of the advanced encryption features of Proton Mail

Code Comparison

FairEmail:

private void handleThreadState(EntityMessage message, JSONObject thread) throws JSONException {
    boolean seen = thread.getBoolean("isRead");
    boolean flagged = thread.getBoolean("isStarred");
    boolean answered = thread.getBoolean("isAnswered");
    db.message().setMessageThread(message.account, message.thread, seen, flagged, answered);
}

Proton Mail:

private fun handleMessageState(message: Message, state: MessageState) {
    message.isRead = state.isRead
    message.isStarred = state.isStarred
    message.isReplied = state.isReplied
    messageRepository.updateMessage(message)
}

Both repositories handle message state updates, but FairEmail uses Java and works with JSON objects, while Proton Mail uses Kotlin and a custom MessageState object. FairEmail's implementation appears more tightly coupled to the database operations, while Proton Mail's approach seems more abstracted with a separate repository layer.

Pros of Fenix

• Larger and more active community, with more frequent updates and contributions
• Broader scope as a full-featured web browser, offering more functionality
• Extensive documentation and well-organized codebase

Cons of Fenix

• More complex codebase due to its broader feature set
• Potentially higher resource usage as a full browser compared to a focused email app
• Steeper learning curve for new contributors due to its size and complexity

Code Comparison

Fenix (Kotlin):

class BrowserFragment : BaseBrowserFragment(), UserInteractionHandler {
    override fun onCreateView(
        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View {
        return super.onCreateView(inflater, container, savedInstanceState)
    }
}

Proton Mail (Java):

public class MailboxFragment extends BaseFragment implements SwipeRefreshLayout.OnRefreshListener {
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_mailbox, container, false);
        return rootView;
    }
}

The code comparison shows that Fenix uses Kotlin, while Proton Mail uses Java. Fenix's codebase appears more modern and concise, leveraging Kotlin's features. Both repositories follow similar architectural patterns for fragment creation, but Fenix's implementation is more streamlined.