E2a

e2a is an open source email API for applications and AI agents. It handles ordinary transactional email such as receipts, verification messages and alerts, and it also gives agents real two way inboxes that can send, receive and reply in thread. It runs as a hosted service or as a self hosted stack under the Apache 2.0 license. It is built for developers, agent focused teams and businesses adding email to products and workflows. Applications call the HTTP API directly or use the TypeScript and Python SDKs, and the same sender can later become a two way inbox with threading, signed webhooks and WebSocket delivery. For agents, a plugin registers a hosted MCP server and an operating skill in Claude Code, Codex, Cursor or any MCP client, authenticating through OAuth rather than a pasted API key. An optional human approval mode pauses sensitive outbound messages so a person can review recipients, subject and body, then approve, edit or reject them, with a configurable time limit and automatic fallback. SPF, DKIM and DMARC evidence is recorded on inbound mail. Hosted pricing is published. Free is $0 per month with 3 agents, 3 custom domains, 3,000 sends per month capped at 20 per day, 1 GiB of storage and an e2a footer. Starter is $10 per month for 10 agents, 5 domains and 20,000 sends. Pro is $20 per month for 25 agents, 10 domains and 50,000 sends. Scale is $99 per month for 250 agents, 150 domains, 200,000 sends and priority support. An add on at $2 per month per inbox adds one inbox and 3,000 sends and lifts the Free daily cap. Inbound mail is free and unmetered on every plan, and higher volumes move to enterprise pricing.