Multi Mail MCP Server

Multi Mail

Gmail, Outlook, Hotmail, Microsoft 365, iCloud, Fastmail, other IMAP mailboxes: search, read, send.

Multi Mail is a remote MCP server run by Lumman Ltd. It puts every mailbox you connect - Gmail, Outlook.com, Hotmail, Microsoft 365, iCloud, Fastmail and other IMAP mailboxes - behind one connector, so an AI client can search all of them in one call and read, draft, send and organise mail in each. This repository holds what clients install: the manifests for Claude Code, Cursor, Gemini CLI, Antigravity and Kiro, four skills and their evals. The server itself is not in it.

Before you start

You need a Lumman account with at least one mailbox connected at https://lumman.co/mcp/account/multi-mail. Sign in there with Google, Microsoft, a passkey or an emailed code. Outlook, Hotmail and Microsoft 365 mailboxes connect with Microsoft sign-in, iCloud and Fastmail with an app password, other IMAP mailboxes with their address and a password, and Gmail with Google sign-in while Google's preview has room; once it is full, a Gmail or Google Workspace mailbox connects with an app password. Each mailbox's permissions - reading, drafts, sending, organising and settings - are set on the same page.

Add it to your client

Claude

Open Multi Mail in Claude's connectors directory, https://claude.ai/directory/connectors/multi-mail, and press Connect. The listing connects at https://lumman.co/mcp/mail.

Claude Code

/plugin marketplace add lumman-lab/multi-mail
/plugin install multi-mail@multi-mail

The plugin adds the connector at https://lumman.co/mcp/mail and the four skills below. The first time a skill reaches the connector, Claude Code asks you to sign in; if it does not, run /mcp and choose the multi-mail server.

Cursor

Add the connector to ~/.cursor/mcp.json:

{
  "mcpServers": {
    "multi-mail": { "url": "https://mail.lumman.co/mcp" }
  }
}

VS Code

Run MCP: Add Server, choose HTTP, paste https://mail.lumman.co/mcp and name it multi-mail. Or add it to your user mcp.json:

{
  "servers": {
    "multi-mail": { "type": "http", "url": "https://mail.lumman.co/mcp" }
  }
}

Gemini CLI

gemini extensions install https://github.com/lumman-lab/multi-mail

The extension adds the connector at https://mail.lumman.co/mcp and the four skills below. Its first call opens Lumman's sign-in in your browser; /mcp auth multi-mail opens it again.

Antigravity

agy plugin install https://github.com/lumman-lab/multi-mail

The plugin adds the connector at https://mail.lumman.co/mcp and the four skills below, for the Antigravity CLI, app and IDE alike. To sign in, run /mcp in the CLI, open multi-mail_multi-mail and choose Authenticate, or in the app or IDE press Authenticate next to it under Agent settings, Customizations; approve on the Lumman page that opens, then paste the code Antigravity's page shows back into Antigravity.

Kiro

In the Powers panel press Add Custom Power, choose Import power from GitHub, paste https://github.com/lumman-lab/multi-mail/tree/main/kiro and press Install. The power adds the connector at https://mail.lumman.co/mcp.

ChatGPT

Works fully on ChatGPT Business, Enterprise and Edu.

1. For a mailbox you connect with a password, add it first in your account, under Add a mailbox.
2. Open chatgpt.com/plugins, press +, then Add custom MCP server.
3. Name it Multi Mail, paste https://mail.lumman.co/mcp, choose OAuth, tick the box and press Create as a plugin.
4. Install it. On the Lumman page, sign in, add a mailbox if none is connected, and approve.
5. In a chat, type @ and choose Multi Mail.

Any other client

Add a remote MCP server at https://mail.lumman.co/mcp: Streamable HTTP, OAuth 2.1 with dynamic client registration. No key or client id is needed.

Signing in

The connector answers a client's first call with where to sign in. The client registers itself with Lumman's authorisation server and opens a Lumman page that names it: sign in, add a mailbox if none is connected, and approve. Every client you approve is listed under AI apps at https://lumman.co/mcp/account/multi-mail, where it can be removed.

Skills

Claude Code, Cursor, Gemini CLI and Antigravity load four skills with the connector, and pick one by themselves when a request matches it. In Claude Code each is also a command, such as /multi-mail:triage.

• triage - what is waiting across every mailbox: what needs a reply, what needs a decision, what can wait. Changes nothing.
• attachments - what a PDF (scanned pages included), Word, Excel or PowerPoint attachment says, read as text.
• drafting - a new message, reply or forward written as a draft and shown to you, then sent only after you say yes to that draft.
• labels - duplicate labels (Outlook categories), and in Gmail unused ones, found and a merge proposed, with nothing changed until you agree.

Examples:

• "What in my Outlook and Gmail still needs a reply?"
• "What total does the invoice Dana sent to my Hotmail come to?"
• "Reply to Sam in Outlook that Friday works, and show me before it goes."

Ready requests

The connector offers these requests ready-made; a client shows them as prompts or commands.

• needs_reply - What needs a reply. Messages across all your mailboxes still waiting for your answer.
• waiting_on - Who is waiting on whom. Who waits on your reply, and whose reply you wait on, across all your mailboxes.
• tidy_newsletters - Tidy newsletters. Find newsletters and promotions across all your mailboxes and archive them.
• morning_brief - Morning brief. A short summary of every inbox, made to run as a Claude scheduled task.
• clean_up_inbox - Clean up my inbox. See who fills an inbox, then clear only the groups you choose.
• keep_tidy - Keep my inbox tidy. Keep the newest few from the senders you choose and archive the rest, set up as a scheduled task.
• manage_rules - Manage my rules. See the rules that file your incoming mail, and add, change or remove only the ones you choose.

Tools

Where your mail goes

Claude and Claude Code send every call to https://lumman.co/mcp/mail, every other client to https://mail.lumman.co/mcp - two addresses of one server, run by Lumman. Signing in runs through the authorisation server those addresses name. Lumman keeps no copy of your mail: each message and attachment is fetched from its provider when a client asks, its words are screened for prompt attacks by Google Cloud's Model Armor - an attachment asked for as the original file is not - as are the words of every draft and send before they reach the provider, and the mail is passed on only to the client you approved - an attachment's original also to whoever holds the 15-minute link that client is given. What the connector passes on, and to whom, is in the privacy policy: https://lumman.co/privacy.

The drafting skill asks the client to show a draft and wait for your yes. What the connector itself enforces is each mailbox's permission to send, set at https://lumman.co/mcp/account/multi-mail: with sending off, nothing is sent, whatever a client asks.

Limits

• Gmail sign-in is in Google's preview, which admits a fixed number of accounts; once its places are spent, a Gmail or Google Workspace mailbox connects with an app password.
• A clear-out, and any change to a draft, in a mailbox connected with a password needs a mail server that names where it moves each message, as iCloud, Fastmail and Gmail do, and clears a Gmail connected that way out of its inbox alone.
• Microsoft lets an Outlook category take a new colour, never a new name.
• Mailboxes connected with a password - iCloud, Fastmail, Gmail and other IMAP mailboxes - take every tool except filters and the vacation responder. iCloud and Fastmail labels are their folders, as your own mail app shows them, and the labels skill leaves them alone.
• Yahoo, AOL, Yandex and Mail.ru mailboxes are not connected.
• Each account has a daily allowance of tool calls; past it, a call is refused with the time the next one is available.
• A message whose words screen as a prompt attack is withheld from the answer that would carry it, and the rest is still given; anything else that screens so is refused, and a call whose screening cannot finish is closed.

Evals

claude plugin eval . runs four cases, one per skill, and thirteen choose-* cases, against invented Hotmail, Gmail, iCloud and IMAP mailboxes answered from fixed mock files under evals/. Each choose-* case is a request in a person's own words - a mailbox by its provider, every account at once, sending, filing, a rule, an auto-reply, clearing out an inbox - that the connector's tools should take, and three are requests no mail tool should take. They read the tools' own descriptions, saved in evals/mocks/multi-mail/_tools.json; the mocks carry no server instructions. Run on 2 November 2026 with Claude Code 2.1.308 and model claude-sonnet-5-5, three runs per case: all thirteen passed 3 of 3.

To see what the skills add, each of the four skill cases ran in two setups with the connector's tools in place: once with the plugin as shipped, once with its skills/ folder removed (claude plugin eval <copy> --ablation none). Run on 18 October 2026 with Claude Code 2.1.292, model claude-sonnet-5-5 and the CLI's default Haiku judge, three runs per case each way:

• triage - lists the two threads waiting for a reply and nothing else: 3 of 3 with the skills and 3 of 3 without. The skill adds nothing measurable here.
• attachments - gives the total and due date read off the invoice PDF: 3 of 3 with and without. The skill adds nothing measurable here.
• drafting - saves the reply as a draft, shows it and asks before sending: 3 of 3 with, 0 of 3 without; without the skills Claude sent the reply at once in every run.
• labels - proposes the merge and asks before changing anything: 3 of 3 with, 0 of 3 without; without them Claude re-labelled messages before asking in every run.

Overall score 1.00 with the skills and 0.74 without. Three runs per case is a small sample, and the mocks answer the same whatever Claude changes.

Security

Report a vulnerability privately through GitHub, as SECURITY.md describes.

Support

Write to the address under Contact Us in Lumman's privacy policy: https://lumman.co/privacy.

Licence

The files in this repository are under the MIT licence in LICENSE. The Multi Mail service they connect to is provided under Lumman's terms: https://lumman.co/terms.