About Mailly
Mailly is an MCP server and plugin for email work in Claude and Codex. It provides scoped tools for managing mail and related workflows, with drafts available for approval before sending.
Key features
- 01Read and send email
- 02Create and manage drafts
- 03Manage domains and contacts
- 04Use templates and campaigns
- 05Manage workflows and webhooks
- 06Scope tools to account permissions
Use cases
- 01Review incoming mail in an agent client
- 02Draft replies for approval before sending
- 03Manage email campaigns and workflows
MCP support
Connect an MCP client to the hosted server at `https://mcp.mailly.site/mcp` using OAuth, or use an API key. The server exposes Mailly tools and optional email and draft card resources, with available tools limited by account scopes.
Configuration
Remote servers need no local install. Pick your client, then copy the config or install in one click.
https://mcp.mailly.site/mcpclaude mcp add --transport http site-mailly https://mcp.mailly.site/mcp{"mcpServers":{"site-mailly":{"type":"http","url":"https://mcp.mailly.site/mcp"}}}Open in Cursor{"servers":{"site-mailly":{"type":"http","url":"https://mcp.mailly.site/mcp"}}}Open in VS Code{"mcpServers":{"site-mailly":{"type":"http","url":"https://mcp.mailly.site/mcp"}}}{"mcpServers":{"site-mailly":{"serverUrl":"https://mcp.mailly.site/mcp"}}}Run commands in a terminal; paste JSON into the client’s MCP config and restart. Servers that need sign-in will prompt on first connect.
Tools
Details
From the project READMEmailly-mcp
The MCP server behind Mailly's connector, plus the Mailly plugin for Claude and Codex.
src/: the MCP server, a Cloudflare Worker. It offers typed tools for Mailly mail, drafts, sending, domains, contacts, templates, campaigns, workflows and webhooks. Every tool calls the Mailly REST API with the caller's Mailly API key, so authentication, billing and workspace isolation all stay in the API.ui/: the MCP Apps UI (email and draft cards), bundled intoui://resources. It is off unlessMCP_APPS=1.plugins/mailly: the plugin for Claude (claude.ai, Cowork and Claude Code) and Codex. It points at the hosted server and adds a skill for working with email safely.
Use the hosted server
Add https://mcp.mailly.site/mcp as a remote MCP server and sign in with your Mailly account (OAuth). In
Claude Code you can install the plugin instead:
/plugin install mailly --marketplace superagents-lab/mailly-mcp
This server is an OAuth protected resource. Mailly's API (https://api.mailly.site/api/auth) is the authorization
server: clients find it through /.well-known/oauth-protected-resource, sign the user in there, and send the
access token here. The server passes the token, or an API key, unchanged to Mailly's REST API, which checks it and
the scopes it carries. The tool list is narrowed to the same scopes (GET /me).
Run it yourself
npm install
npm run dev # wrangler dev on http://localhost:8787/mcp
Call /mcp with Authorization: Bearer <your Mailly API key> (from https://mailly.site/app/developers).
Without the MAILLY_API service binding it calls MAILLY_API_URL (default https://api.mailly.site) over
the internet. To host your own copy, change the mcp.mailly.site route in wrangler.jsonc. OAuth sign-in only
works at https://mcp.mailly.site/mcp, because Mailly issues tokens for that resource; elsewhere use an API key.
Develop
npm run typecheck
npm test # builds dist/worker.js and runs it in Miniflare against a stub API
The Mailly server repository runs its OAuth and end-to-end tests against dist/worker.js from a sibling
checkout of this repository.
server.json is the listing in the MCP Registry as
site.mailly/mcp. The site.mailly namespace is proven by a DNS TXT record on mailly.site, so publish with
mcp-publisher login dns --domain mailly.site --private-key <key> and mcp-publisher publish from a machine that
holds the key. Bump version for each release.
License
MIT
Comments
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