Conversation

Someone needs to create an SMTP for the 21st century. Something that forces servers to:
- Refuse to relay a message without end-to-end encryption and a digital signature
- Require unknown senders to solve a cryptographic hash problem per message
- Require a TLS certificate from a CA on both sides of any connection
- Use 8-bit attachments (no Base64)
- Drop HTML in favor of Markdown
- Not support external embedding