VaultMail — a mail server for AI agents
A self-hosted disposable-inbox service that speaks to both humans and AI agents — an agent can create its own inbox and wait for a verification code without a human ever opening a browser.
What it is
Disposable inboxes are an old idea. What’s new here is who they’re for: VaultMail is built so that its primary user isn’t a human — it’s an AI agent.
An agent automating some signup flow can say “create me an inbox”, then “wait for the verification code” — and receive the parsed OTP as a value. No screenshots, no HTML parsing, no human opening a browser. This happens over MCP (Model Context Protocol) — the standard for plugging tools into AI assistants.
How it works
Underneath sits a real mail server: Postfix accepts messages over SMTP, a Python agent writes them into PostgreSQL, Redis pub/sub fans them out live — to the browser over SSE and to agents over MCP. Dovecot provides IMAP for classic mail clients. One backend serves three entrances — web, IMAP and MCP — from a single codebase.
The most fun feature: checking whether an email address has been used elsewhere. A background job scans 100+ public sites for traces of a signup with that address — a useful signal for whether a “disposable” inbox actually looks like a real account.
What I learned
That running your own mail server in 2026 is both easier and scarier than it sounds. Outbound mail reputation is a fragile thing — which is why the mail lives on its own isolated machine, far away from everything else.