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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.

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Choose a surface

Pre-claim smx_agent_ tokens are mailbox-compatible only. Owner-approved Sending-resource smx_agent_ tokens can send. Pre-claim self-registered agent tokens include mailbox.read and email.receive, not email.send.

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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.