sendmux-sdkBLOCK
Official monorepo of SDKs, CLI, and MCP servers for Sendmux email APIs across TypeScript, Python, Go, PHP, Rust, and Ruby.
Overview
From the repository's own README, as read at the audited commit. Badges and raw HTML are left out.
[](https://www.npmjs.com/package/@sendmux/sdk) [](https://pypi.org/project/sendmux-sdk/) [](https://pkg.go.dev/sendmux.ai/go/v3) [](https://crates.io/crates/sendmux) [](https://github.com/Sendmux/sendmux-sdk/actions/workflows/ci.yml) [](https://www.npmjs.com/package/@sendmux/sdk) [](LICENSE)
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
94930e1491b4OBSERVED · 2026-10-07Connect
Built from this server's own package name, version and transport as found in its source — not copied from anyone's documentation, so it cannot drift against a page we do not control. Replace the environment placeholders with a token scoped to the least it needs.
claude mcp add sendmux-mcp --env SENDMUX_MAILBOX_API_KEY=${SENDMUX_MAILBOX_API_KEY} --env SENDMUX_MANAGEMENT_API_KEY=${SENDMUX_MANAGEMENT_API_KEY} --env SENDMUX_SENDING_API_KEY=${SENDMUX_SENDING_API_KEY} -- npx -y [email protected]claude mcp add sendmux-mcp --env SENDMUX_MAILBOX_API_KEY=${SENDMUX_MAILBOX_API_KEY} --env SENDMUX_MANAGEMENT_API_KEY=${SENDMUX_MANAGEMENT_API_KEY} --env SENDMUX_SENDING_API_KEY=${SENDMUX_SENDING_API_KEY} -- None sendmux-mcp==2.2.0Exposed tools (29)
26 read · 2 write · 1 destructive. Blast radius: 1 tool can delete or overwrite — an agent that can be talked into calling a tool can be talked into calling this one.
| Tool | Risk | Description |
|---|---|---|
confirm_delete | destructive | Parks the task on one elicitation before doing the (pretend) deletion. |
greet | write | A sync-only tool: never runs as a task. |
multi_input | read | Parks the task on two elicitations at once, so they can be answered separately. |
protocol_error_job | read | Raises a protocol-level error: `failed` with an inlined `error`. |
remote_contract_probe | read | Fixture operation |
slow_compute | read | Sleeps for *seconds*, so a cancel can land while it is still running. |
test_audio_content | read | Returns WAV audio. |
test_custom_headers | read | Mirrors an argument into an `Mcp-Param-Message` header (SEP-2243). |
test_elicitation | read | Requests user input via elicitation. |
test_elicitation_sep1034_defaults | read | Tests elicitation with default values per SEP-1034. |
test_elicitation_sep1330_enums | read | Tests elicitation with enum schema improvements per SEP-1330. |
test_embedded_resource | read | Returns an embedded resource. |
test_error_handling | read | Always returns an error. |
test_image_content | read | Returns a PNG image. |
test_input_required_result_capabilities | read | Asks only for the input methods this client declared it can answer. |
test_input_required_result_elicitation | read | Asks the client one elicitation question, then greets the answer. |
test_input_required_result_list_roots | read | Asks the client for its roots, then reports them back. |
test_input_required_result_multi_round | read | Asks two dependent questions across three rounds. |
test_input_required_result_multiple_inputs | read | Asks for elicitation, sampling, and roots in a single round. |
test_input_required_result_request_state | read | Carries opaque state across the round trip and confirms it came back. |
test_input_required_result_sampling | read | Asks the client to sample an answer, then echoes the sampled text. |
test_input_required_result_tampered_state | read | Round-trips sealed state so a tampered echo is rejected by the framework. |
test_missing_capability | read | Requires the client to have declared the sampling capability (SEP-2575). |
test_multiple_content_types | read | Returns mixed text, image, and resource content. |
test_reconnection | write | Closes the POST stream mid-call so the client must resume (SEP-1699). |
test_sampling | read | Requests LLM sampling via the client. |
test_simple_text | read | A simple text tool for conformance testing. |
test_tool_with_logging | read | Sends log notifications during execution. |
test_tool_with_progress | read | Reports progress notifications. |
Trust audit
BLOCKgrade F · trust 46/100 Do not install this without reading the findings. The audit found something that could harm you or your machine.
| Layer | What it checks | Result |
|---|---|---|
| L0 | Provenance & inventory | FAIL |
| L1 | Static analysis of the code | FAIL |
| L2 | Instruction surface (what it tells the agent) | PASS |
| L3 | Class-specific surface | WARN |
| L4 | Behavioural (sandbox) | SKIPPED |
What the source does
- Filesystem
- declared (10 observation(s))
- Network
- declared (1 observation(s))
- Shell
- declared (6 observation(s))
- Dependencies
- pinned
- Secrets in source
- found
Findings (25)
get-delivery-payload.ts
const { stdout } = await exec(command, args, {return create_sending_client(api_key="smx_mbx_test_attachment_replay", base_url="https://sending-replay.test"), requests
secret = "smx_mbx_private_fixture" if field == "api_key" else "oauth-private-fixture"
return { status: 201, body: envelope({ credential: { public_id: "key_owned", secret: "smx_mbx_private_test" } }) };if (req.method === "POST") return { status: 201, body: envelope(boundary === "key_delete" ? { credential: { public_id: "key_owned", secret: "smx_mbx_private_test" } } : { id: "folder_owned", name: "FiapiKey: "smx_agent_test_mailbox",
confirm_delete
.release-please-manifest.json
.rubocop.yml
.ruby-version
.golangci.yml
package = importlib.import_module(package_name)
api_client = importlib.import_module(f"{package_name}.api_client")configuration = importlib.import_module(f"{package_name}.configuration")package = importlib.import_module(package_name)
api_client = importlib.import_module(f"{package_name}.api_client")import { inviteAgentOwner } from "../../agent-auth.js";import { SendmuxCommand } from "../../base-command.js";import { registerAgent } from "../../agent-auth.js";import { SendmuxCommand } from "../../base-command.js";import { SendmuxCommand } from "../../base-command.js";yield f"http://127.0.0.1:{server.server_port}/api/v1", requestsyield f"http://127.0.0.1:{server.server_port}/api/v1", requests, responsesyield "http://127.0.0.1:#{server.addr[1]}/api/v1", requestsGates applied: no_behavioural_pass.
94930e1491b4full audit observations/trust-audit/mcp-server/sendmux__sendmux-sdk.json · Report an issue / request a re-scanAudit history
Every audit this server has had. A grade with a past is a grade somebody is still checking.
| Date | Source | Verdict | Grade | Score | Change |
|---|---|---|---|---|---|
| 2026-10-07 | 94930e1491b4 | BLOCK | F | 46 | first audit |
Questions
What is the sendmux-sdk MCP server?
Official monorepo of SDKs, CLI, and MCP servers for Sendmux email APIs across TypeScript, Python, Go, PHP, Rust, and Ruby.
What tools does sendmux-sdk expose?
29 in total: 26 read-only, 2 that write, and 1 that can delete or overwrite (confirm_delete). Every one is listed on this page with its risk.
Is sendmux-sdk safe to connect to an agent?
No — not without reading the findings first. The audit graded it F (46/100) and found 2 critical or high issues in the source. Each one is listed on this page with the file and line it is on. Separately from the audit: 1 of its tools can destroy data, so scope the token you give it to what you actually need.
What credentials does sendmux-sdk need?
It reads CHOCOLATEY_API_KEY, GH_TOKEN, GITHUB_TOKEN, INTERNAL_API_SECRET, POSTHOG_PROJECT_TOKEN, SENDMUX_ACCESS_TOKEN, SENDMUX_API_KEY, SENDMUX_MAILBOX_API_KEY, SENDMUX_MANAGEMENT_API_KEY, SENDMUX_MCP_ALLOW_UNAUTHENTICATED_HTTP, SENDMUX_MCP_AUTHORIZATION_SERVERS and SENDMUX_MCP_HTTP_BEARER_TOKEN from the environment. Give it a token scoped to the least it needs — an agent that can be talked into calling a tool can be talked into calling it with your credentials.
How does sendmux-sdk run?
It speaks stdio and streamable-http, so it runs as a local process your client starts. It is published on npm as @sendmux/sending at 1.6.0.
How current is this page?
The grade is for one exact copy of the source (94930e1491b4), read on 2026-10-07. The repository is watched and re-audited when it changes.