Yes, Fastmail has an official MCP server. It runs at https://api.fastmail.com/mcp, you sign in with OAuth, and you choose read, write or send access on the consent screen. It covers mail, contacts and calendars, and Fastmail’s help article says attachments aren’t supported over MCP.
Fastmail announced the server in April 2026. Details below are from Fastmail’s own blog post and help article, as of November 2026. Check them before you rely on any detail, because these products change quickly. If MCP is new to you, start with what MCP is, and why it matters for email.
The short version
- Server URL:
https://api.fastmail.com/mcp, added as a remote server in your AI client. - Sign-in: OAuth 2.0 with your normal Fastmail password, so no app password is needed. Fastmail’s help article offers an API token as an alternative.
- Access levels: read-only, write and send. You can pick more than one.
- What it covers: mail, contacts and calendars. Attachments aren’t available through MCP.
- Clients: Fastmail’s help article names Claude Desktop, ChatGPT and Perplexity, and gives step-by-step instructions for Claude only.
- Revoking: connected clients are listed in Fastmail’s settings, where you can remove each one.
What can the Fastmail MCP server do?
Fastmail’s help article describes three access levels, and you choose which to grant when you connect:
| Level | What the AI client can do |
|---|---|
| Read-only | Search and read mail, contacts and calendars |
| Write | Draft replies, move, delete and organise mail, update contacts and calendars |
| Send | Send email on your behalf |
Separating these is good design. You can start with read-only, see how your assistant behaves, and add more later. It’s the same split we recommend looking for in any email MCP server.
Two limits are worth knowing before you start. Fastmail’s help article says attachments aren’t supported over MCP, so an assistant can tell you a contract arrived but can’t open the PDF. And the help article doesn’t list the individual tools, so you’ll see the exact set only once your client connects.
How do you connect Fastmail to Claude?
Fastmail’s help article gives these steps for Claude:
- Sign in to Claude.
- Click Customize on the left, then Connectors.
- Click the plus sign, then Add custom connector.
- Enter any name, such as “Fastmail”, and the URL
https://api.fastmail.com/mcp. - Complete the OAuth sign-in with your Fastmail account and choose the access levels you want.
Anthropic explains how custom connectors work, and which Claude plans include them, in its help article on remote MCP connectors. On Team and Enterprise plans, an owner has to add the connector first.
One limitation: Fastmail says Claude doesn’t support connecting more than one Fastmail account. If you need two, Fastmail suggests other clients, such as ChatGPT, may handle it.
Can you use it with ChatGPT, Claude Code or other clients?
The same URL works in any client that supports remote MCP servers. The general steps are the same everywhere: add the server URL, sign in through OAuth, and choose your access levels.
Fastmail names ChatGPT and Perplexity but doesn’t document their steps, and support for custom MCP servers in those products depends on the client and your plan. Check the client’s own documentation.
For Claude Code, Anthropic documents adding a remote HTTP server from the command line. A command like this registers the server:
claude mcp add --transport http fastmail https://api.fastmail.com/mcpThen run /mcp inside Claude Code and follow the browser steps to complete the OAuth sign-in.
If you’d rather not use OAuth, Fastmail’s help article says you can use an API token instead. Its developer documentation explains where to create one in your settings. Treat a token like a password: anyone who has it can use your account up to its scopes.
Which Fastmail plans include it?
Fastmail doesn’t name a plan requirement for MCP, but it does restrict third-party apps on its Basic plan. Its pricing page says use with third-party apps isn’t supported on the Basic plan, and we found no statement on whether that covers MCP. If you’re on Basic, test it or ask Fastmail support before planning around it.
What should you check before you connect it?
Start with read-only. Add write and send once you’ve seen what your assistant does with your mail. An assistant that can send can also be steered by a malicious email, which is called prompt injection. We cover the risk in giving an AI assistant access to your inbox, safely.
Remember where the mail goes. Everything the assistant reads is sent to the AI provider you use, under that provider’s terms. Fastmail’s help article notes that it has no control over how connected AI clients store, process or use your data. It also warns about legal and compliance implications for sensitive mail, such as health or legal correspondence.
Know your data residency. Fastmail’s EU region keeps the primary copy of your mail in Amsterdam, but its data residency documentation says a replica is kept in the US, and backups, logs and debug systems are US-based. If that matters for your compliance, our Fastmail alternative article covers the difference in more detail.
Know how to turn it off. You’ll find connected clients in Fastmail’s settings under Privacy & Security, with the date of first and most recent access. To revoke one, open Connected apps & API tokens, then Manage app passwords and access, click the client and choose Remove access. Fastmail notes that this can’t be undone, so you’d connect again from scratch.
Does Fastmail build AI into its mail?
No. Fastmail says it hasn’t integrated AI into Fastmail. The MCP server is another API endpoint, it’s optional, and nothing changes for you if you never use it.
That keeps the assistant entirely your choice. The trade-off is that everything an assistant does depends on the client you connect and the access you grant.
How Lettio compares
Lettio also offers an MCP server, with a few differences that matter for some teams. Our email MCP server is part of the mailbox: add https://mcp.lettio.eu/mcp, sign in with OAuth, and connect up to 10 mailboxes at once.
- Attachments. Your agent can open attachments. Text and PDF files come back as text, and images as images.
- Sending. A new connection can read, organise and draft, and you send from the card in Claude yourself. Sending on its own is something you allow when you sign in, and then only as your own address.
- Jurisdiction. Your mailbox is hosted on our own EU servers, under the GDPR. Your AI provider still processes whatever your agent reads.
The trade-offs are real. It only works with a Lettio mailbox, so you’d have to move your mail. Lettio isn’t end-to-end encrypted: our servers can read your mail, because search and agents work on it.
If you’re happy on Fastmail, its official server is a good way to connect an assistant, and you don’t need to switch. If EU hosting matters to you, or you want attachments in reach of your agent, Lettio is in a closed beta and you can request access.