mailmcp

mailmcp is a self-hosted MCP server that gives ChatGPT, Claude and other MCP clients access to your e-mail over IMAP and SMTP: several mailboxes at once, any provider, attachments in both directions. This repository is the prebuilt distribution (minified bundles in dist/, no build step) under a commercial licence; it runs as a free tier without a key, and the source code is available to customers on request.

Ask "What came in from accounting this week?" and get one answer across Gmail, iCloud and the company mail server: the invoice as a download link, a reply already drafted.

When to use it

Use mailmcp when you have more than one mailbox, a provider without an official connector, or you need attachments. As of September 2026 the official Gmail and Outlook connectors in ChatGPT and Claude handle one mailbox each and cannot send attachments.

	Official connectors	mailmcp
Mailboxes	one per connector	several at once, one token
Providers	Gmail, Outlook	Gmail, iCloud, Fastmail, Yahoo, Zoho, Seznam.cz and any IMAP/SMTP server with password sign-in, including your own domain (Microsoft 365 / Outlook.com do not work with passwords, OAuth planned)
Attachments	read some, send none	one-hour download links; sending from the mailbox, from a file the assistant uploads, or by forwarding
Authentication	OAuth grant held by the AI vendor	an app password, encrypted in your browser into a token; the server keeps one master key and no database
Hosting	the vendor's	yours: Vercel, Docker, any Node 22 host, or Claude Desktop without a server
Cost	included in the assistant's plan	free with a signature in sent mail, or one payment (€19 / €149)

Quickstart

Requirements. Node 22 (or Vercel, or Docker), an HTTPS address (ChatGPT and Claude only connect over HTTPS), and an app password for each mailbox. Gmail: turn on 2-Step Verification first, otherwise Google hides the app-passwords page (organisation policies or Advanced Protection can hide it too). Microsoft 365 / Exchange Online and Outlook.com do not work yet: Microsoft does not allow password sign-in over IMAP (OAuth planned).

1. Deploy. Click the Vercel button above; it asks for MAILMCP_KEY (32 random bytes as base64url, node -e "console.log(require('crypto').randomBytes(32).toString('base64url'))") and MAILMCP_LICENSE (your key, or empty for the free tier). Or run it yourself:

   docker build -t mailmcp . && docker run -d -p 8080:8080 \
     -e MAILMCP_KEY=… -e MAILMCP_LICENSE=… -e MAILMCP_PUBLIC_URL=https://mail.example.com mailmcp
   # without Docker: node dist/node.js with the same variables
   

2. Open https://<your-server>/start and follow it: on the setup page pick the provider, paste the e-mail and the app password, tick what the assistant may do (reading is on by default; drafts are a good second step; sending only with an allowlist of recipients). The page encrypts the password in your browser and hands you one token.

3. Connect. ChatGPT → Settings → Apps → Create → URL https://<your-server>/mcp; claude.ai → Settings → Connectors → Add custom connector. Sign in with the token. Then ask: "List my mail accounts."

Try it without deploying. The shared server at mailmcp.ai/setup runs this same code; create a token there and connect. The operator of any shared server can technically see your configuration while it serves your requests, which is why companies run their own.

Claude Desktop, no server. Download mailmcp.mcpb from the latest release, open it in Claude Desktop, paste the configuration from /setup → "Values for your own deployment".

Behind a reverse proxy set MAILMCP_PUBLIC_URL or MAILMCP_TRUST_PROXY=1. Company mail servers on private addresses need MAILMCP_ALLOW_PRIVATE_MAIL_HOSTS=1. Changing MAILMCP_KEY invalidates every token. All variables: .env.example.

What the assistant can do

Every tool is gated by the permissions in the token, per mailbox:

Permission	Tools
read (default)	list_accounts, list_folders, search_messages (Gmail syntax on Gmail), get_message, get_thread, get_attachment (one-hour download link), ChatGPT search/fetch
draft	create_draft, upload_attachment, request_upload (a one-hour upload link the assistant fills itself)
send	send_message, send_draft, forward_message, only to addresses on your allowlist
modify	modify_message (flags, folders)
delete	trash_message; nothing is ever deleted permanently

Every tool is listed to the client; a call the token does not permit fails with an error naming the missing permission.

Security and data flow

• Credentials. The setup page encrypts mailbox passwords in your browser into a split-key token. The server holds one master key, decrypts the configuration only while serving your request, keeps it in memory for at most 15 minutes after the last one, and has no database and no copy of your mail.
• What leaves the server. IMAP/SMTP traffic to your mail provider and tool results to your assistant (so the AI vendor sees the results of every tool call, never the passwords). Licence verification is offline. The only links to the vendor are the Buy buttons.
• Prompt injection. Message bodies are marked as untrusted data, hidden text is stripped and header fields are sanitized, which reduces the risk of instructions planted in an e-mail; it cannot make a model immune.
• Protocol. OAuth 2.1 with PKCE, dynamic client registration and client metadata documents, encrypted tokens with replay guards, login throttling. Read-only defaults, send allowlists, no permanent deletion.
• Revocation. Delete the app password at your provider; the token is then useless no matter who holds it. Rotating MAILMCP_KEY invalidates all tokens on a server.
• Review. An internal, AI-assisted security review of version 0.4.1 (September 2026) with every finding, fix and accepted trade-off is public: mailmcp.ai/audit.

Pricing

Free	Personal, €19 once	Unlimited, €149 once
All tools included, up to 2 mailboxes per token (tokens created before 0.7.0 keep 5). Every message the assistant composes (drafts, sends, forwards) ends with "Sent with mailmcp.ai".	One person, up to 5 mailboxes per token, no signature, on your own server or in Claude Desktop.	One server for the whole company, unlimited users and mailboxes.

All 0.x updates are included; a 1.0 upgrade may carry a fee, and 0.x keeps working. 14-day refund, no questions asked. Company deployment, €990: two hours of online onboarding on your Vercel or cloud, Unlimited licence included. Buy at mailmcp.ai/pricing: the key appears right after payment and Stripe e-mails the invoice.

Updating

Releases are tagged here and listed in CHANGELOG.md. If you deployed with the Vercel button, Vercel created your own copy of this repository: pull the new tag into it (git pull https://github.com/kojott/mailmcp-dist.git main and push), and Vercel deploys the push. Docker and Node: pull, rebuild or restart. To roll back, deploy the previous tag. Your tokens keep working across versions as long as MAILMCP_KEY stays the same.

Questions people ask

Google says the app-passwords setting "is not available for your account". Turn on 2-Step Verification and reload; if it is still missing, an organisation policy or Advanced Protection is blocking app passwords.

I lost my token. Tokens cannot be recovered. Create a new one on the setup page (with an edit password this time, so you can load and change it later) and swap it in your assistant.

Can the assistant send mail on its own? Only if you enabled sending, and only to addresses on the allowlist. Drafts are the safer default.

Attachment links. Download and upload links are valid for one hour and carry the token in encrypted form; anyone with the link can use it during that hour.

Licence, support, reporting problems

The licence agreement is in LICENSE (English translation first, the Czech original governs): one key, one running installation, no redistribution; removing the licence check or the free-tier signature is prohibited. This is closed-source software, so pull requests are not accepted, but bug reports in Issues are welcome. Security problems: write to info@swingingdogs.com instead of opening an issue. Privacy policy: https://mailmcp.ai/privacy, terms: https://mailmcp.ai/terms.

Guide for people: mailmcp.ai/docs. Guide for assistants, paste the link into ChatGPT or Claude and let it walk you through: mailmcp.ai/llms.txt. Support: jiridolejs.cz/kontakt.

Version 0.7.3. Made in Prague by Jiří Dolejš.