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Email Inbox API + Sending by Sendmux

io.github.Sendmux/sendmux-mcpv1.5.0Email

AI email inbox and sending tools with attachments, search, live events, and webhooks.

In-path gate · all MCP tools

Using Email Inbox API + Sending by Sendmux in Claude, Cursor, Gemini CLI, Cline, or Zed?

MCP tool contracts can change remotely with no version bump. The mcpindex gate pins each contract and HOLDs the call when it drifts-before your agent acts. Zero credentials. This is not the package install for this server itself (use Install this server for that).

Install the mcpindex gate (one command)

Rewrites your MCP host config so each server launches behind the gate. Inspect first: curl -fsSL https://mcpindex.ai/install.sh | less

uv tool install mcpindex-gate && mcpindex-config-wire
Auditable install path →Watch it hold a drift →
Trust verdict · v1 advisory · method
REVIEWstatus: PARTIALfresh until 2026-08-24 06:04 UTC
screened 2026-07-25tier: scannedgranularity: description-levelsource: registry

Semantic screen found no manipulation pattern in the description. Conformance probe not yet run.

mcpindex.integrity.descriptionpassINFO

evidence“No malicious instructions found”via static_description

Limits of this verdict
  • - Semantic screen only - the deterministic conformance probe has not run on this server
  • - Confidence is reported but not yet calibrated (v1)
  • - Screen reads the tool description, not the live behavior
  • - advisory
  • - registry description only no input schema
  • - screen model 8b

Semantic screen: an LLM judge reads the tool description for hidden instructions (status PARTIAL). A pass means the description is not lying, not that the tool is safe: a high-capability tool with an honest description still warrants caution. The deterministic conformance probe has not been run on this server yet, so the screen here is semantic-only. Posture: advisory. Confidences are reported but not yet calibrated (calibrated=false at v1). Full verdict history is not shown on this page.

Own this server? Screen its description →

That verdict was true at screening time (snapshot 2026-08-04).

Contracts can change after screening, with no version bump. The gate pins Email Inbox API + Sending by Sendmux’s tool contracts on first sight and holds any silent change before your agent acts - the check that keeps being true on Tuesday.

See your first HOLD in 2 minutes →

Related: how to trust an MCP server · screen before install · silent contract drift

Embed this badge

A live verdict badge for your README or listing. It reflects the current screen, links back here, and updates when the verdict does.

Markdown
[![mcpindex](https://mcpindex.ai/api/v1/badge/io-github-sendmux-sendmux-mcp)](https://mcpindex.ai/server/io-github-sendmux-sendmux-mcp)
HTML
<a href="https://mcpindex.ai/server/io-github-sendmux-sendmux-mcp"><img src="https://mcpindex.ai/api/v1/badge/io-github-sendmux-sendmux-mcp" alt="mcpindex verdict" height="20" /></a>
Environment variables
SENDMUX_MCP_SURFACES
required

Tool surfaces to run locally.

SENDMUX_MAILBOX_API_KEY
requiredsecret

Mailbox API key for Mailbox API and Sending API tools.

SENDMUX_MANAGEMENT_API_KEY
requiredsecret

Root API key for Management API tools.

SENDMUX_SENDING_API_KEY
secret

Optional send-capable smx_mbx_ key or owner-approved smx_agent_ token for Sending API tools when it differs from the Mailbox API key.

MCP quality score · maturity, not trust · methodology
freshness
25
completeness
20
installability
25
documentation
15
stability
10
Alternatives in Email
Mermail
app.mermail/mcp

Email inbox API for AI agents: read, search, draft, send, and triage mail over Streamable HTTP.

MCP Emails
com.mcpemails/emails

Read, search, send, organize, draft and schedule email across your inboxes from any MCP client.

io.github.SergioRico1/thrd
io.github.SergioRico1/thrd

Thrd MCP: agent email tools for events/threads, safe send/reply, usage, trust and security.