Pros of MailHog

• More feature-rich with a web UI, API, and support for multiple storage backends
• Cross-platform compatibility (Windows, macOS, Linux)
• Active development and community support

Cons of MailHog

• More complex setup compared to FakeSMTP
• Requires Go runtime environment
• Larger resource footprint

Code Comparison

MailHog (Go):

func CreateMail(from string, to []string, subject string, body string) (*data.Message, error) {
    msg := &data.Message{
        From:    from,
        To:      to,
        Subject: subject,
        Body:    body,
    }
    return msg, nil
}

FakeSMTP (Java):

public void createMail(String from, String[] to, String subject, String body) {
    MimeMessage message = new MimeMessage(session);
    message.setFrom(new InternetAddress(from));
    for (String recipient : to) {
        message.addRecipient(Message.RecipientType.TO, new InternetAddress(recipient));
    }
    message.setSubject(subject);
    message.setText(body);
}

Both projects serve as fake SMTP servers for testing email functionality in applications. MailHog offers a more comprehensive solution with its web interface and API, making it suitable for larger projects and teams. FakeSMTP, on the other hand, provides a simpler, lightweight option that may be preferable for smaller projects or quick testing scenarios. The choice between the two depends on the specific requirements of the project and the development environment.

Pros of maildev

• Web-based interface for viewing and testing emails
• Supports both SMTP and API-based email sending
• More actively maintained with recent updates

Cons of maildev

• Requires Node.js runtime
• More complex setup compared to FakeSMTP
• Larger codebase and dependencies

Code comparison

FakeSMTP (Java):

public void start() {
    if (!running) {
        running = true;
        Thread smtpServerThread = new Thread(new Runnable() {
            @Override
            public void run() {
                startServer();
            }
        });
        smtpServerThread.start();
    }
}

maildev (JavaScript):

async start() {
  if (this.port) {
    await this.smtp.listen(this.port, this.host)
    logger.info(`MailDev SMTP Server running at ${this.host}:${this.port}`)
  }

  if (this.webPort) {
    await this.web.listen(this.webPort, this.host)
    logger.info(`MailDev webapp running at ${this.host}:${this.webPort}`)
  }
}

Both projects serve as fake SMTP servers for testing email functionality in applications. FakeSMTP is a simpler, Java-based solution, while maildev offers a more feature-rich experience with a web interface and additional capabilities. The choice between them depends on specific project requirements and the preferred development environment.

Pros of Mailcatcher

• Web-based interface for viewing captured emails
• Supports multiple email formats (HTML, plain text)
• Easy integration with various development environments

Cons of Mailcatcher

• Requires Ruby installation and dependencies
• May have performance issues with large volumes of emails

Code Comparison

FakeSMTP (Java):

public static void main(String[] args) {
    SMTPServer smtpServer = new SMTPServer(new SimpleMessageListenerAdapter(new ConsoleMessageHandler()));
    smtpServer.setPort(2525);
    smtpServer.start();
}

Mailcatcher (Ruby):

require 'mailcatcher'

MailCatcher.run! do
  serve_messages
  serve_web
end

Key Differences

• FakeSMTP is written in Java, while Mailcatcher is written in Ruby
• FakeSMTP focuses on simplicity and lightweight operation, while Mailcatcher offers more features through its web interface
• FakeSMTP stores emails as .eml files, whereas Mailcatcher keeps them in memory
• Mailcatcher provides a more user-friendly interface for viewing and managing captured emails
• FakeSMTP may be easier to set up in Java-based environments, while Mailcatcher is more suitable for Ruby-centric development stacks

Both tools serve the purpose of capturing and inspecting emails during development, but they cater to different language ecosystems and offer varying levels of functionality.