Inbound MCP server

Connect any MCP client (Claude, Cursor, OpenCode, ChatGPT, agents) to Inbound: manage domains, endpoints, addresses, emails, Guard rules and mailboxes, which are virtual email accounts that agents can read and send from.

Endpoint: https://inbound.new/mcp (Streamable HTTP, stateless)

Three ways to connect

The Inbound API enforces mailbox scopes and limits. An account can set protocols, allowed_ips, storage_quota_bytes, daily_send_limit and self_service with create_mailbox or update_mailbox. The password works as an MCP bearer token and for IMAP (imap.inboundemail.com:993) and SMTP (smtp.inboundemail.com:465) only where the protocol and IP are allowed. For MCP, the allowlist must include the MCP server’s outgoing IP, not the agent’s. Changing protocols, allowed IPs or self-service immediately closes open IMAP sessions. The daily limit counts only sends and replies authenticated by the mailbox password, not account-key sends.

{
  "mcpServers": {
    "inbound": {
      "type": "http",
      "url": "https://inbound.new/mcp",
      "headers": { "Authorization": "Bearer " }
    }
  }
}

Leave out headers to use OAuth. Discovery follows the MCP authorization spec: the 401 points to https://inbound.new/.well-known/oauth-protected-resource/mcp, the authorization server is https://inbound.new/api/auth (dynamic client registration, PKCE), and tokens carry the inbound:account scope for the https://inbound.new/mcp audience. This server verifies them against Inbound’s JWKS and forwards them to the API.

x-inbound-api-key: is also accepted. Clients that only speak STDIO can use npx mcp-remote https://inbound.new/mcp --header "Authorization:Bearer ${INBOUND_API_KEY}".

Limit the tool list

Add ?toolsets= (or an x-inbound-toolsets header) with any of domains,endpoints,addresses,emails,mailboxes,guard, e.g. https://inbound.new/mcp?toolsets=mailboxes,emails.

Give an agent its own inbox

1. With the account key: create_mailbox { "address": "[email protected]", "sending_name": "Support Agent" }.
2. Give the returned password to the agent as its bearer token.
3. The agent loops: list_messages { unread_only: true } → read_message → reply → update_message { is_archived: true }.

Mailboxes, read state and sent mail are stored by Inbound, so they show up in the dashboard and over IMAP too.

Tools (account key)

• Domains: list_domains, get_domain, create_domain, update_domain, delete_domain, enable_domain_dkim
• Endpoints: list_endpoints, get_endpoint, create_endpoint, update_endpoint, delete_endpoint, test_endpoint
• Addresses: list_email_addresses, get_email_address, create_email_address, update_email_address, delete_email_address
• Emails: list_emails, get_email, send_email, reply_to_email, update_email, cancel_scheduled_email, pause_scheduled_email, resume_scheduled_email, retry_email_delivery, list_threads, get_thread, list_attachments, download_attachment
• Mailboxes: list_mailboxes, create_mailbox, update_mailbox, delete_mailbox, rotate_mailbox_password, get_mailbox, list_mailbox_messages, read_mailbox_message, update_mailbox_message, get_mailbox_thread, send_from_mailbox, reply_from_mailbox, download_mailbox_attachment
• Mailbox folders: list_mailbox_folders, create_mailbox_folder, rename_mailbox_folder, delete_mailbox_folder
• Folder messages (by folder path and UID, not account email ID): list_folder_messages, get_folder_message, get_folder_message_raw, set_message_flags, move_message, copy_message, delete_folder_message, expunge_folder, append_message, list_folder_message_attachments, download_folder_message_attachment
• Mailbox filters: list_mailbox_filters, get_mailbox_filter, create_mailbox_filter, update_mailbox_filter, delete_mailbox_filter, reorder_mailbox_filters, apply_mailbox_filters. Enabled filters run on new received mail; use apply_mailbox_filters to process an existing folder.
• Mailbox spam: get_mailbox_spam_settings, set_mailbox_spam_settings, add_spam_list_entry, remove_spam_list_entry. These affect only this mailbox, not the account verdict.
• Mailbox activity: list_mailbox_activity reads one mailbox’s log; list_account_activity reads across the account, optionally filtered by mailbox_id. Both list sign-ins, IMAP session events, quota errors and send failures, newest first. Events are retained for 30 days; message content and passwords are never logged.
• Guard: list_guard_rules, get_guard_rule, create_guard_rule, update_guard_rule, delete_guard_rule, check_guard_rule, generate_guard_rule

Development

bun install
bun run dev        # http://localhost:5454/mcp, against production unless INBOUND_API_URL is set
bun run typecheck
INBOUND_API_KEY=... bun run stdio   # STDIO transport

Deployed on Vercel (team inbound, project inbound-mcp) as one function, api/mcp.ts. inbound.new/mcp rewrites to it from the main app.