Sendmux SDKs

Official SDK, CLI, and MCP workspace for Sendmux.

• Product documentation: sendmux.ai/docs
• Management API reference: sendmux.ai/docs/api/introduction
• Mailbox API reference: sendmux.ai/docs/mailbox-api/introduction
• Sending API reference: sendmux.ai/docs/sending-api/introduction
• MCP guide: sendmux.ai/docs/ai-integrations/mcp

Packages

Quick start

Install only the package for the surface you need.

npm install @sendmux/sending
pip install sendmux-sending
go get sendmux.ai/go/v3@v3.0.0
cargo add sendmux
composer require sendmux/sending:^2.1
gem install sendmux-sending

Use send-capable smx_mbx_* keys or owner-approved Sending-resource smx_agent_* tokens for Sending clients. Use smx_mbx_* keys or scoped smx_agent_* tokens for Mailbox clients. Use root smx_root_* keys for Management clients. Agent tokens remain limited by server-side scopes; pre-claim self-registered agent tokens do not include email.send.

OAuth authentication

TypeScript, Python, Go, PHP, Ruby, and Rust surface clients accept a bare REST OAuth access token or a provider that resolves one before each request. Use the explicit token API below; API-key configuration continues to validate key prefixes.

Choose one credential source. Your application owns secure storage and refresh coordination. Request resource=https://sendmux.ai/api; each API still checks its required scopes and granted surface. The CLI manages browser login and token refresh with sendmux auth:login; use sendmux auth:logout to revoke its connection.

OAuth setup and lifecycle.

Command-line access

For command-line access, install the CLI:

brew install sendmux/tap/sendmux
npm install -g @sendmux/cli
sendmux agent:register my-agent --mailbox-local-part my-agent --default --json

Agent registration does not require an existing account or API key. It creates a local profile with a durable, revocable credential for reading and receiving mail. To send, invite the owner with sendmux agent:invite-owner owner@example.com --profile my-agent; after the owner accepts and approves sending, Sending API commands exchange and cache a one-hour delegated token automatically.

For MCP clients, install sendmux-mcp or connect to the hosted MCP endpoint:

pip install sendmux-mcp
sendmux-mcp-mailbox --help

The hosted MCP endpoint is https://mcp.sendmux.ai/mcp. Local MCP commands support stdio and HTTP transports; hosted MCP uses OAuth and does not require manual API keys or custom OAuth endpoints.

For A2A 1.0 clients, discover the hosted HTTP+JSON service from https://a2a.sendmux.ai/.well-known/agent-card.json. It exposes the same curated mailbox, management, and sending operations with an OAuth grant bound specifically to https://a2a.sendmux.ai/a2a/v1.

For AI-agent frameworks, first-party tool wrappers are available:

npm install @sendmux/ai-sdk ai zod   # Vercel AI SDK: sendmux({ apiKey }) returns a ToolSet
pip install langchain-sendmux        # LangChain: SendmuxToolkit(api_key=...).get_tools()