@multimail/mcp-server

@multimail/mcp-server

MCP server for MultiMail. Give your agent its own email address with graduated human oversight — from full approval to autonomous sending.

Quick start

npx @multimail/mcp-server

Set MULTIMAIL_API_KEY for full access, or run without it to create an account first. Get a key at multimail.dev.

By using MultiMail you agree to the Terms of Service and Acceptable Use Policy.

Setup

Option A: Remote server (recommended)

No install required. Connect directly to our hosted server. Authenticates via OAuth in the browser.

{
  "mcpServers": {
    "multimail": {
      "type": "url",
      "url": "https://mcp.multimail.dev/mcp"
    }
  }
}

Works with Claude.ai, Claude Desktop, Claude Code, and any client that supports remote MCP servers.

Option B: Local server (stdio)

Run the server locally. API key is passed as an environment variable.

{
  "mcpServers": {
    "multimail": {
      "command": "npx",
      "args": ["-y", "@multimail/mcp-server"],
      "env": {
        "MULTIMAIL_API_KEY": "mm_live_...",
        "MULTIMAIL_MAILBOX_ID": "01KJ1NHN8J..."
      }
    }
  }
}

Where to add this

Client	Config file
Claude Code	~/.claude/.mcp.json
Claude Desktop	claude_desktop_config.json
Cursor	.cursor/mcp.json in your project
Windsurf	~/.codeium/windsurf/mcp_config.json
Copilot (VS Code)	.vscode/mcp.json in your project
OpenCode	mcp.json in your project
ChatGPT Desktop	Settings > MCP Servers
Any MCP client	Consult your client's docs for config location

Environment variables

Variable	Required	Description
MULTIMAIL_API_KEY	Yes	Your MultiMail API key (mm_live_...)
MULTIMAIL_MAILBOX_ID	No	Default mailbox ID. If not set, pass mailbox_id to each tool or call list_mailboxes first.
MULTIMAIL_API_URL	No	API base URL. Defaults to https://api.multimail.dev.

First-run setup

On first use, MultiMail will prompt you to configure your mailbox. You can also run this explicitly using the configure_mailbox tool:

• Oversight mode: How much human approval is required (gated_send, monitored, autonomous, etc.)
• Display name: Sender name shown in emails
• CC/BCC defaults: Automatically copy addresses on all outbound emails
• Scheduling: Enable/disable scheduled send and set default gate timing
• Signature: Email signature block

If you skip this step, MultiMail will remind you on your first tool call.

Tools

Tool	Description
list_mailboxes	List all mailboxes available to this API key
configure_mailbox	Set up mailbox preferences: oversight mode, display name, CC/BCC, scheduling, signature
send_email	Send an email with a markdown body. Supports attachments, idempotency_key, and send_at for scheduled delivery.
check_inbox	List emails with filters: status, sender, subject, date range, direction, attachments, cursor pagination
read_email	Get full email content. Returns trusted metadata and untrusted body as separate content blocks.
reply_email	Reply to an email in its existing thread. Supports attachments and idempotency_key.
download_attachment	Download an email attachment as base64 with content type
get_thread	Get all emails in a conversation thread with participants and metadata
cancel_message	Cancel a pending or scheduled email
schedule_email	Schedule an email for future delivery with a required send_at time. Edit or cancel before it sends.
edit_scheduled_email	Edit a scheduled email's delivery time, recipients, subject, or body before it sends
update_mailbox	Update mailbox settings (display name, oversight mode, signature, webhooks)
update_account	Update account settings (org name, oversight email, physical address)
delete_mailbox	Permanently delete a mailbox (requires admin scope)
request_challenge	Request an ALTCHA proof-of-work challenge for account creation (no API key required)
create_account	Create a new account with a solved PoW challenge (no API key required)
resend_confirmation	Resend the activation email with a new code (no API key required)
activate_account	Activate an account using the code from the confirmation email (no API key required)
tag_email	Set, get, or delete key-value tags on emails (persistent agent memory)
add_contact	Add a contact to your address book with optional tags
search_contacts	Search address book by name or email
get_account	Get account status, plan, quota, sending enabled, enforcement tier
create_mailbox	Create a new mailbox (requires admin scope)
request_upgrade	Request an oversight mode upgrade (trust ladder)
apply_upgrade	Apply an upgrade code from the operator
get_usage	Check quota and usage stats for the billing period
list_pending	List emails awaiting oversight decision (requires oversight scope)
decide_email	Approve or reject a pending email (requires oversight scope)
delete_contact	Delete a contact from the address book
check_suppression	List suppressed email addresses
remove_suppression	Remove an address from the suppression list
list_api_keys	List all API keys (requires admin scope)
create_api_key	Create a new API key with scopes (requires admin scope + operator approval; send+oversight combinations rejected to prevent self-approval)
revoke_api_key	Revoke an API key (requires admin scope)
get_audit_log	Get account audit log (requires admin scope)
delete_account	Permanently delete account and all data (requires admin scope)
wait_for_email	Block until a new email arrives matching filters, or timeout (max 120s)
create_webhook	Create a webhook subscription for real-time email event notifications
list_webhooks	List all webhook subscriptions for this account
delete_webhook	Delete a webhook subscription

How it works

• You write email bodies in markdown. MultiMail converts to formatted HTML for delivery.
• Incoming email arrives as clean markdown. No HTML parsing or MIME decoding.
• Threading is automatic. Reply to an email and headers are set correctly.
• Sends return pending_scan status while the email is scanned for threats. If your mailbox uses gated oversight, the status transitions to pending_send_approval for human review. Do not retry or resend.
• Verify other agents by checking the X-MultiMail-Identity signed header on received emails.

Development

npm install
npm run dev   # Run with tsx (no build needed)
npm run build # Compile TypeScript
npm start     # Run compiled version

Testing

echo '{"jsonrpc":"2.0","method":"tools/list","id":1}' | MULTIMAIL_API_KEY=mm_live_... node dist/index.js

License

MIT