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

How do I install npubmail?

Clone npubmail from https://github.com/obvioussummer46/npubmail and configure it as an MCP server in your client (Claude Desktop, Cursor, or VS Code).

Is npubmail open source?

Yes, npubmail is open source under the MIT license. Source code is available at https://github.com/obvioussummer46/npubmail.

What category does npubmail belong to?

npubmail is listed under Communication MCP servers on MCPFind.

npubmail — MCP Server for Communication

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-0.2.0.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.

Compatible MCP Clients

npubmail works with any MCP-compatible client. Copy the config snippet from the Configuration section above and add it to the file shown for your client, then restart the application.

Claude Desktop~/Library/Application Support/Claude/claude_desktop_config.jsonRestart Claude Desktop completely for changes to take effect.

Cursor~/.cursor/mcp.jsonRestart Cursor for changes to take effect.

VS Code.vscode/mcp.jsonReload VS Code window for changes to take effect.

Windsurf~/.codeium/windsurf/mcp_config.jsonRestart Windsurf for changes to take effect.

Claude Code.mcp.jsonSave at the project root, then start Claude Code in that project and review the MCP server approval prompt. Keep real credentials out of shared files.

npubmail