Blindrelay Agent Plugin

Send transactional email and manage sending domains, OTLP observability, and suppression through any Agent-Plugins-compatible client (Cursor, Claude Code, Codex, Copilot, VS Code, …) — without reinventing the setup.

This is a portable Agent Plugins 1.0 package. It bundles:

• One MCP server (blindrelay, Streamable HTTP → https://api.blindrelay.app/mcp) exposing the same tools as the Blindrelay CLI: send, domains_*, usage, usage_history, delivery_stats, suppression_*, audit_list, otlp_*, delivery_settings_*.
• Four Agent Skills that teach an agent when and how to use those tools, and the no-content-on-disk invariant that must be honored on every send.

Blindrelay is a zero-content EU email relay: message body, subject, and headers live in process RAM only until delivery; the recipient address is stored as a bcrypt hash. See references/no-content-on-disk.md.

Layout

agent-plugin/
├── plugin.json                       # Agent Plugins 1.0 manifest (portable; Cursor/Code/Codex/Copilot)
├── mcp.json                          # blindrelay MCP server (Streamable HTTP, no secrets)
├── .cursor-plugin/                   # Cursor-optimized layer (optional, single-click auth)
│   ├── plugin.json                   #   Cursor manifest + variables (BLINDRELAY_API_KEY)
│   └── mcp.json                      #   MCP config using ${BLINDRELAY_API_KEY} / ${BLINDRELAY_MCP_URL}
├── skills/
│   ├── setup/SKILL.md                # onboarding + auth
│   ├── send-mail/SKILL.md            # send transactional email
│   ├── manage-domains/SKILL.md       # add/verify/rotate-dkim/remove domains
│   └── delivery-observability/SKILL.md  # OTLP, webhook, usage, stats, suppression, audit
├── references/
│   ├── tools.md                      # full tool reference + scopes + error codes
│   ├── no-content-on-disk.md         # the load-bearing invariant
│   └── transports.md                 # streamable-http vs stdio, self-hosted
├── README.md
└── LICENSE

The root plugin.json + mcp.json are the portable Agent Plugins 1.0 entry (works in every compatible client). The .cursor-plugin/ directory is a Cursor-only layer that lets Cursor users set the API key once via a dashboard variable instead of editing MCP headers by hand. Non-Cursor clients ignore .cursor-plugin/ and use the portable manifest. Cursor users: if your client lists the plugin twice, prefer the .cursor-plugin/ entry and ignore the root one.

Install

Install through your client's plugin UI by pointing it at this directory (or the published registry entry, when listed). For example, in Cursor: Settings → Plugins → Add → select the agent-plugin/ directory.

Configure auth (one time)

Agent Plugins 1.0 does not let a plugin carry secrets, so the API key is client-managed. There are two paths:

Cursor (single-click, recommended)

The .cursor-plugin/ layer declares two dashboard variables. Set them once under Plugins → Configure:

Variable	Required	Purpose
BLINDRELAY_API_KEY	yes	Scoped API key from https://blindrelay.app/keys (one-time reveal). Stored only in the Cursor dashboard, never in the plugin repo.
BLINDRELAY_MCP_URL	no	MCP endpoint. Defaults to the production endpoint https://api.blindrelay.app/mcp.

Cursor substitutes ${BLINDRELAY_API_KEY} into the Authorization: Bearer … header and ${BLINDRELAY_MCP_URL} into the server URL automatically. No manual header editing.

Other clients (portable)

1. Create a scoped API key at https://blindrelay.app/keys (reveal once, copy br_…). Scopes:
   • send → Free plan, can call send.
   • read + write → Starter+, unlocks domains / suppression / OTLP / delivery settings / audit / usage.
2. In your client's MCP settings for the blindrelay server, add the header:

   Authorization: Bearer br_…
   

3. Verify by calling usage (needs read) or domains_list (needs read). A 401 means the key/header is missing; a 403 scope_missing means the key lacks the scope.

Prefer a local binary + env? See references/transports.md for the stdio variant using blindrelay-mcp.

Use

Ask your agent in plain language:

• "Send a password reset email to the user from noreply@mydomain.com"
• "Add mail.example.com as a sending domain and show me the DNS records"
• "Verify the DKIM for my domain"
• "Point delivery events to my Grafana OTLP endpoint"
• "How many emails have I sent this month?"
• "Show me the suppression list"
• "What changed in my tenant in the last week?" (audit log)

The skills activate automatically based on intent. The agent will never log a recipient address or email body after a send.

Safety properties

• No content on disk. Body/subject/headers are RAM-only; recipient is a bcrypt hash. Enforced by backend/tests/no_content_on_disk.rs on every release. The skills reinforce this on the agent side.
• No secrets in the plugin. The API key never ships in mcp.json headers or stdio env; it lives in your client's secret store (Cursor dashboard variable, or your client's MCP auth settings).
• Customer-owned observability. Delivery events go to your OTLP endpoint and/or delivery webhook — your Grafana / Datadog / Honeycomb is the system of record.

Validation

The package is checked on every MR by the blindrelay_agent_plugin_lint_job CI job (scripts/validate-agent-plugin.py): manifest closed-schema, MCP transport validity, no embedded secrets, Cursor ${VAR} placeholders all declared in variables, skill frontmatter + name/dir match, and internal markdown links. Run it locally:

just agent-plugin-lint        # or: python3 scripts/validate-agent-plugin.py

License

MIT — applies only to the contents of this agent-plugin/ package (manifests, skills, reference docs). The Blindrelay product itself is licensed separately and remains proprietary; see the repository root README.md. See LICENSE.