Sendmux SDKs

Official Sendmux SDK workspace.

This repository publishes modular TypeScript packages first, with Python, Go, PHP, Ruby, MCP, and CLI packages following the build plan.

TypeScript Packages

Install only the surface you need:

npm install @sendmux/sending
npm install @sendmux/mailbox
npm install @sendmux/management

Or install the optional umbrella package:

npm install @sendmux/sdk

Package	API surface	API key
`@sendmux/sending`	Send email	`smx_root_*`
`@sendmux/mailbox`	Read and manage one mailbox	`smx_mbx_*`
`@sendmux/management`	Manage domains, mailboxes, sending accounts, billing, and webhooks	`smx_root_*`
`@sendmux/core`	Shared runtime helpers and types	n/a
`@sendmux/sdk`	Optional umbrella re-export	surface-specific

Usage

Sending:

import {
  createSendingClient,
  sendingSendEmail,
} from "@sendmux/sending";

const client = createSendingClient({
  apiKey: process.env.SENDMUX_API_KEY!,
});

const response = await sendingSendEmail({
  client,
  body: {
    from: "sender@example.com",
    to: ["recipient@example.com"],
    subject: "Hello from Sendmux",
    html: "<p>Hello.</p>",
  },
});

console.log(response.data.message_id);

Mailbox:

import {
  createMailboxClient,
  mailboxListMessages,
} from "@sendmux/mailbox";
import { paginate } from "@sendmux/core";

const client = createMailboxClient({
  apiKey: process.env.SENDMUX_MAILBOX_API_KEY!,
});

for await (const message of paginate((cursor) =>
  mailboxListMessages({
    client,
    query: { cursor, limit: 50 },
  }),
)) {
  console.log(message.id);
}

Management:

import {
  createManagementClient,
  managementListDomains,
} from "@sendmux/management";

const client = createManagementClient({
  apiKey: process.env.SENDMUX_API_KEY!,
});

const domains = await managementListDomains({ client });
console.log(domains.data);

Runtime Helpers

@sendmux/core provides:

API key prefix validation for smx_root_* and smx_mbx_*
typed ApiError and SuccessEnvelope
cursor pagination via paginate
retrying fetch with exponential backoff, jitter, Retry-After, and X-RateLimit-Reset
helpers for Idempotency-Key, If-Match, If-None-Match, and ETag handling

Versioning

SDK packages follow the Sendmux API contract version:

Sending packages track the sending API contract.
Mailbox and management packages track the app API contract.
Patch versions may differ by package for SDK-only fixes.

Development

pnpm install --frozen-lockfile
pnpm build

The SDKs are generated from committed OpenAPI snapshots. Generated output must stay in the same pull request as any API contract change.