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Fastmail MCP server: the official one, access levels, setup
- Fastmail has had an official MCP server since 22 April 2026, for mail, contacts and calendars. You sign in with your normal Fastmail password.
- You pick read-only, write or send. Write includes deleting mail. It can't open attachments yet.
- It reaches the whole account: you can't limit it to some folders or dates. You can revoke it at any time.
Fastmail's MCP server lets an AI assistant such as Claude or ChatGPT work with your Fastmail mail, contacts and calendars. MCP (Model Context Protocol) is the standard way these assistants connect to other apps. Of the big mail providers, Fastmail is the only one with an official MCP server you can just use: no developer program, no Cloud project, no admin. It's well made: you sign in on Fastmail's own page, choose what the agent may do, and see every connected app in your settings.
If you're on Fastmail and want Claude or ChatGPT to work with your mail, start here. You'll see how to connect it, what each access level lets an agent do, and what it can't do yet. For other providers, see email MCP servers compared.
Fastmail MCP options compared
Checked on 27 October 2026, from Fastmail's blog and help center, the GitHub projects and MailTag's MCP docs.
| Option | How it gets into your account | Read and search | Organize | Delete | Send | Attachments |
|---|---|---|---|---|---|---|
| Fastmail's official server | Your Fastmail account | Yes | Yes | Yes | Yes | No |
| fastmail-mcp (community) | An API token from Fastmail | Yes | Yes | Yes | Yes | Yes |
| Generic IMAP MCP server | App password | Yes | Yes | Yes | Yes | Yes |
| MailTag's MCP | App password, via MailTag | Yes | Yes | No | Yes | Yes |
Only the first is made by Fastmail. On it, each action depends on the level you pick: read-only, write (organize, draft and delete) or send. MailTag's MCP only sees email it labeled in the last 30 days, and each action is off until you allow it. Community and IMAP servers vary from one to another.
How Fastmail's MCP server works
Fastmail announced the server on 22 April 2026 (Fastmail blog). Fastmail is clear that it hasn't added AI to Fastmail itself: nothing changes unless you connect an assistant.
Its help page lists three access levels you pick when you sign in. You can grant any combination (Fastmail Help):
- Read-only: search and read mail, contacts and calendars.
- Write: draft replies, move, delete and organize mail, update contacts and calendars.
- Send: send email on your behalf.
Attachments aren't available yet. Fastmail doesn't say which plans include the server. Its API tokens, the other way to connect, aren't available on the Basic plan (Fastmail Help).
Connect it to Claude
- In Claude, open Customize → Connectors, click + and Add custom connector.
- Enter a name and the address
https://api.fastmail.com/mcp. - Sign in to Fastmail with your normal password and choose the access level.
On Claude's Free plan you can add one custom connector. On Team and Enterprise, an admin adds it first and you then connect (Claude Help). By default Claude asks before it uses a connector's tools. Claude doesn't support adding more than one Fastmail account.
Connect it to ChatGPT and other apps
ChatGPT accepts a server added by its address only on some plans. OpenAI's help says full support, including actions that change things, is for Business, Enterprise and Edu workspaces, on the web, where an admin adds it. Pro users can add it to read only (OpenAI Help). In Claude Code, Cursor and similar apps, add the same address to the app's MCP servers and sign in the same way.
Revoke access
Every connected assistant appears in Settings → Privacy & Security, under Connected apps & API tokens. You see its access level, when it first connected and when it was last used. Click Manage app passwords and access, choose the assistant and click Remove access.
What to keep in mind
- Start with read-only. Write sounds harmless but includes deleting mail.
- The whole account. Each level applies to your whole mailbox, contacts and calendars. There's no "only this folder".
- Your data goes to the agent. Fastmail says it can't control how a connected AI app stores or uses your data. It suggests getting advice before connecting mail with health, legal or other people's personal data. See AI agent email privacy.
- Hidden instructions. An agent with the send level can be pushed by a crafted email to send something. See email prompt injection.
For developers
- Community servers filled the gap before April 2026. Some still add things such as attachments, but for most people the official server is the better choice.
- Server:
https://api.fastmail.com/mcp, with OAuth 2.0. An API token of type MCP also works, with its own read, change and send scopes; tokens aren't available on Basic. - fastmail-mcp: unofficial, MIT, runs on your machine (Node.js 20+) or as a Claude Desktop extension. Uses Fastmail's JMAP API with an API token; covers attachments, contacts and calendars (CalDAV).
- local-fastmail-mcp: API token, archived; its author recommends the official server.
Fastmail and MailTag's MCP server
MailTag connects to Fastmail with an app password, which Fastmail's Basic plan doesn't include (Fastmail Help). On Fastmail it marks each new email with your own categories as keywords, by default without moving anything. It runs on its servers in the EU and doesn't store email content.
Its MCP server at https://mailtag.app/mcp covers less ground than Fastmail's, on purpose, and lets you narrow it per agent:
| Fastmail's server | MailTag's MCP | |
|---|---|---|
| Read email | Yes | Yes |
| Organize email | Yes | Yes |
| Write drafts | Yes | Yes |
| Send email | Yes | Yes |
| Delete email | Yes | No |
| Contacts and calendars | Yes | No |
| Search all your mail | Yes | No |
| Open attachments | No | Yes |
| Limit to some folders or categories | No | Yes |
| Limit by date | No | Yes |
| Hide sender, subject or text | No | Yes |
| Limit who it sends to and how often | No | Yes |
On Fastmail, deleting comes with the write level. On MailTag, organizing means moving an email to another category or editing categories and saved views. It never deletes email or takes it out of the mailbox, and it only sees email it labeled in the last 30 days.
Dates go back 30 days, 7 days, today or from now on. Drafts land in your mailbox's Drafts folder for you to send. Sending is a separate switch: replies only or new email too, only to people you've replied to or anyone, up to 10, 50 or 200 a day.
You can use both: Fastmail's server for an agent that needs your whole account, contacts or calendar; MailTag's for one that should only see, say, Needs reply from this week. See the MCP docs.
FAQ
Does Fastmail have an official MCP server?
Yes, announced on 22 April 2026. It works with Claude, with ChatGPT on some plans, and with any app that lets you add an MCP server by its address.
Which Fastmail plans include the MCP server?
Fastmail doesn't say. Its API tokens, the other way to connect, aren't available on the Basic plan, which also has no IMAP.
Do I need an app password for Fastmail's MCP server?
No. You sign in with your normal Fastmail password, on Fastmail's own page.
Can Fastmail's MCP server delete email?
Only with the write level, which includes moving and deleting mail. The read-only level can't change anything.
Can I connect two Fastmail accounts to Claude?
Not at the moment. Fastmail's help says Claude doesn't support adding several Fastmail accounts; other apps may.
Can the agent read attachments through Fastmail's MCP server?
Not yet. Fastmail says attachments aren't supported for now.