Show HN: Agent Message Transfer Protocol (amtp-protocol.org)

Agent Message Transfer Protocol (AMTP) is a new federated, asynchronous messaging protocol for autonomous systems that extends the familiar agent@domain addressing model with structured JSON payloads, schema validation, guaranteed delivery semantics, and built-in multi-agent coordination patterns. AMTP uses DNS TXT discovery (e.g., _amtp.yourdomain.com IN TXT "v=amtp1;gateway=https://..."), a gateway-per-domain architecture, HTTPS transport, and HTTP endpoints for message exchange. It provides at-least-once delivery with idempotency and retry logic, optional AGNTCY schema integration for payload validation, and workflow primitives for parallel, sequential, and conditional coordination. A reference gateway, protocol spec, and a Python SDK with async support are available to accelerate adoption, and SMTP bridging is supported for compatibility with legacy email flows. For the AI/ML community, AMTP matters because it standardizes cross-organization agent-to-agent communication without a central authority, enabling interoperable, reliable orchestration of services, tool calls, and autonomous agents. Compared to SMTP, HTTP APIs, or existing agent specs (MCP, A2A, ANP, ACP), AMTP deliberately favors a lightweight, federation-friendly design that reuses Internet primitives (DNS/HTTPS) while adding structured data, schema validation, and delivery guarantees. That makes it practical for both inter- and intra-organizational automation, but adoption will depend on gateway deployments, schema convergence, and operational trust models.