OpenAI Codex

Prerequisites

• Codex CLI (or the Codex IDE extension) installed
• A MailCraft API key with the scopes you want the agent to have — create one under Settings → API keys.

Setup

1. 1

   Set your API key

   Export it from your shell profile (~/.zshrc, ~/.bashrc, …) so it never sits in the config file:

   terminal Copy

   export MAILCRAFT_API_KEY="sk_live_your_api_key"

2. 2

   Add the server

   Edit ~/.codex/config.toml:

   ~/.codex/config.toml Copy

   [mcp_servers.mailcraft]
   url = "https://mcp.mailcraft.host"
   bearer_token_env_var = "MAILCRAFT_API_KEY"

   Codex reads the bearer token from the named environment variable, so the key is never written to disk.

3. 3

   Restart Codex

   Start a new Codex session to load the configuration.

4. 4

   Verify the connection

   Run /mcp to confirm mailcraft is connected, then ask:

   codex Copy

   List all my MailCraft domains

Example prompts

Once connected, try asking OpenAI Codex:

• Hook up a MailCraft webhook handler for email.bounced in this app
• Show me the last five emails that failed and why
• Create a "Trial ending" template and a draft campaign for my trial users segment

See every tool the agent can use in the MCP server reference.