I'm building a platform of AI agents, and each agent can have its own email address. AgentMail handles that. You create an inbox via their REST API and they POST to your webhook when mail arrives.
On the agent side, it just gets tools: send email, reply to email, list inbox, read message. Those tools call the AgentMail API. So the fake implements the same interface.. same send/reply/list/read methods, but recording calls instead of making HTTP requests. You can pre-populate inboxes with test messages, simulate "username taken" errors, etc.
AgentMail is actually one of the simpler fakes because there's no internal state to maintain. Sending a message doesn't affect what you'd read back from your own inbox. Some of the other fakes (like the database or file storage) need to actually simulate state in memory so writes are visible to subsequent reads. This one is closer to a stub.
We know the founder of this pretty well actually. It's not really an alternative. They are an MCP that is building an email-like layer for coding agents to talk to each other. We are an actual email inbox provisioned via API for agents to email agents or humans.
we have a few things in place, allowlists and permissions act as a layer. also beginning some work on prompt isolation within api soon. but having an isolated identity + data within a separate agentic inbox also puts less risk of your personal email data being injected - which is most people's main concern
Cloudflare/SES works if you want raw email sending and receiving. If you want threading, parsing, storage, retrieval, logic, filtering, labeling, search -- you'll need to build it out yourself.
We're devs ourselves so ik the first thought is usually "how hard can it be?" in our validation, we thought it was hard enough to build a startup around :) these things are easier said than done, and no one in 2026 should be stitching together email workflows. especially not agents
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