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npubmail

Official registry Productivity

Email inbox for AI agents, owned by a Nostr key. No signup or API key. Receive codes, read, send.

Source code Website Documentation

Install

Add this to your client's MCP configuration (Claude Desktop: claude_desktop_config.json; Cursor: .cursor/mcp.json; VS Code and others use the same "mcpServers" shape).

MCPB package https://github.com/obvioussummer46/npubmail/releases/download/v0.2.1/npubmail-mcp-0.2.1.mcpb

Environment variables

  • NPUBMAIL_NAME Preferred mailbox name (becomes <name>@npubmail.com if free). Optional.

Documentation

From the project's README on GitHub, refreshed weekly. Links open on GitHub.

Contents
  1. npubmail clients
  2. Install
  3. Use it
  4. What the service does
  5. Your key is your account
  6. Licence

npubmail clients

Email for AI agents, owned by a Nostr key. No signup, no password, no API key: the agent's keypair is the account.

This repository holds the open clients for the hosted service at npubmail.com:

  • cmd/npubmail: command-line client
  • cmd/npubmail-mcp: MCP server (Claude Code, Hermes, OpenClaw, any MCP client)
  • client/: Go library (EnsureMailbox, CreateAlias, WaitFor, Send, ...)
  • skills/npubmail/SKILL.md: agent skill
  • docs/: HTTP API, the sealed-mail format (SEAL.md) with test vectors, and Python/JS examples

Install

One click (Claude Desktop and other MCPB clients): download npubmail-mcp-0.2.1.mcpb and open it.

Listed in the official MCP Registry as com.npubmail/npubmail.

curl -fsSL https://npubmail.com/install | sh       # prebuilt, checksummed binaries
# or from source:
go install github.com/obvioussummer46/npubmail/cmd/npubmail-mcp@latest
go install github.com/obvioussummer46/npubmail/cmd/npubmail@latest

MCP config:

mcp_servers:
  npubmail:
    command: npubmail-mcp          # talks to https://npubmail.com
    timeout: 660                   # wait_for_* can block up to 600 s

Use it

npubmail init myagent                      # -> myagent@npubmail.com (key at ~/.config/npubmail/nsec)
npubmail alias --from github.com --ttl 24  # disposable, sender-locked address
npubmail code --timeout 120                # block until mail arrives, print the OTP

Agents: start at https://npubmail.com/llms.txt.

What the service does

  • Receive: free. Disposable aliases per signup, codes and links extracted.
  • Encrypted at rest: each message is sealed to the owner's Nostr key (see docs/SEAL.md); the server cannot read stored mail.
  • Send: replies to people who wrote to you are free, and so is mail to other npubmail mailboxes. Mailing a new recipient costs a few sats over Lightning, per message, with no account balance.
  • Inbound TLS (STARTTLS), DKIM/SPF/DMARC on outbound.

Your key is your account

~/.config/npubmail/nsec is the only credential. Back it up; there is no reset. The clients sign every request locally (NIP-98) and never send the key anywhere.

Licence

MIT (LICENSE): clients, library, protocol packages, skill and examples. The server is not in this repository.

Frequently asked questions

What is npubmail?

Email inbox for AI agents, owned by a Nostr key. No signup or API key. Receive codes, read, send.

How do I install npubmail?

Follow the installation steps in its documentation, shown on this page and in its repository.

Does npubmail need an API key?

Its registry entry lists no required key or secret. Some features may still need an account with the service it connects to.

Is npubmail open source?

Yes. Its code is on GitHub under the MIT license.

Who maintains npubmail?

It is published by obvioussummer46. AI.tn lists it but does not maintain or endorse it.

From the official MCP Registry. Listing is not an endorsement: review a server's code and permissions before giving it access to your data.