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Sendmux SDKs give your application package-managed clients for the Sending, Mailbox, and Management APIs. Use an umbrella package when one application needs more than one API surface. Use a surface package when you want a smaller dependency for one job.
Create the credential in Sendmux before you install a package. Sending clients accept a send-capable smx_mbx_ key or owner-approved Sending-resource smx_agent_ token. Mailbox clients accept smx_mbx_ keys or scoped smx_agent_ tokens. Management clients use team-scoped smx_root_ keys.
TypeScript, Python, Go, PHP, Ruby, and Rust clients also accept REST OAuth tokens and token providers. Use the token option documented for your language; API-key prefix requirements apply to API-key configuration.

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Choose a surface

Durable smx_agent_ tokens are mailbox-compatible and include mailbox.read and email.receive, not email.send. After owner acceptance and approval, exchange the durable token for a one-hour Sending-resource token before sending.

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Choose a package family

CLI

Install the Sendmux CLI with Snap, Homebrew, or npm for terminal workflows.

MCP servers

Connect AI tools to Sendmux docs and authorised product tools.

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Next steps

Versioning and support

Understand package releases, compatibility, and support details.

API keys

Create scoped credentials before using an SDK.

Sending API

Review the Sending API contract used by sending SDK packages.

Management API

Review the Management API contract used by management SDK packages.

Mailbox API

Review the Mailbox API contract used by mailbox SDK packages.