CODEX

Install Mermail
in Codex.

Install the Mermail plugin so Codex maps MERMAIL_API_KEY into MCP, loads 11 skills, and can list mailboxes, draft replies, and complete checkout.

Open API Keys Read Skills docs

Why Codex

Built for the agent you already use.

Mermail gives Codex a dedicated inbox and payment layer so verification, checkout, and receipts stay in the same loop.

Plugin wires MCP via env_http_headers

Eleven skills plus 72 hosted tools

No API key pasted into the plugin manifest

CLI available for batch and CI scripts

Three steps to connect.

Export MERMAIL_API_KEY

Create a project key (sk-proj-…) in Settings → API Keys. Codex maps MERMAIL_API_KEY via env_http_headers. Restart Codex after exporting.

Auth

export MERMAIL_API_KEY="sk-proj-YOUR_KEY"

Install the Mermail plugin

Adds 11 skills and wires MCP to console.mermail.app/mcp with env_http_headers. Streamable HTTP only — do not use SSE.

Install

codex plugin marketplace add Nudgen-Marketing/mermail-skills
codex plugin add mermail@mermail

New session, then verify

Start a new Codex session so MCP reloads. Run /mcp and confirm Mermail tools, then try a read-only tool.

Verify

/mcp
Ask: "List my Mermail mailboxes" (tool: list_mailboxes)
Ask: "Use Mermail to draft a short test email"

Questions, answered.

Auth, transports, and how to confirm the connection before you trust the agent.

Where do I create an API key?+

Open console Settings → API Keys, create a project key (sk-proj-…), and export MERMAIL_API_KEY in the environment your agent uses.

Can I add MCP without the plugin?+

Append this to ~/.codex/config.toml and replace the key, then start a new session and run /mcp: [mcp_servers.mermail] url = "https://console.mermail.app/mcp" http_headers = { "x-api-key" = "sk-proj-YOUR_KEY" }

Why not OAuth for Codex?+

The GitHub marketplace plugin uses x-api-key via MERMAIL_API_KEY. Official ChatGPT / Codex Plugins Directory (when published) uses OAuth Apps Connected plus Skills.

How do I know Mermail is connected?+

Ask the agent to list your Mermail mailboxes. A healthy connection exposes the hosted MCP tools, including list_mailboxes.

Can I use the CLI instead?+

Yes. Install mermail-cli (Node.js 22+) for scripted Sold API calls: mermail doctor, mermail auth check, mermail workspaces list, mermail mailboxes list. Prefer CLI for batch work and MCP for interactive inbox tools. Destructive CLI commands need --yes when non-interactive.

See all integrations

Integration index

Claude

Install the Mermail plugin so Claude can provision an inbox, read verification mail, and finish paid workflows without leaving the terminal.

ChatGPT

Add Mermail as a custom ChatGPT connector. Streamable HTTP plus OAuth — no API key in the connector. Then ChatGPT can list mailboxes, read mail, and finish paid workflows.

Cursor

Install the hosted MCP server with OAuth. Cursor discovers Protected Resource Metadata after a 401, then your agent can read mail and act on payments inside the IDE.

OpenClaw

Point OpenClaw at hosted MCP with Streamable HTTP and x-api-key. Probe the connection, then let the agent manage inboxes and payment receipts.

Hermes

Add Mermail as a Streamable HTTP MCP server in Hermes Agent. OAuth opens a browser, then the agent can list mailboxes, read mail, and finish paid workflows in chat.

Install Mermailin Codex.