Applications to chat only using mail id

Here are some popular applications that allow you to chat only using your email ID:

1. ProtonMail: A secure and private email service that allows you to chat with others using your email address.
2. Tutanota: A German-based email service that offers end-to-end encryption and allows you to chat with others using your email address.
3. Mailvelope: A browser extension that allows you to send and receive encrypted emails, including chat-like conversations.
4. Cryptomail: A secure email service that allows you to chat with others using your email address, with end-to-end encryption.
5. Posteo: A German-based email service that offers end-to-end encryption and allows you to chat with others using your email address.
6. Mailfence: A secure email service that offers end-to-end encryption and allows you to chat with others using your email address.
7. S-Mail: A secure email service that allows you to chat with others using your email address, with end-to-end encryption.
8. Gmail's Confidential Mode: While not a dedicated chat app, Gmail's Confidential Mode allows you to send encrypted emails that can be used for chat-like conversations.

Please note that while these applications offer secure and private communication, they may not be as convenient or feature-rich as traditional chat apps like WhatsApp, Facebook Messenger, or Slack.