MailBridge

What your AI can do with it

• Read and search. Latest messages, search by sender, recipient, subject, text, date range and folder; any message in full with its list of attachments; save attachments as files.
• Write. New email, reply in the thread (with Cc and Bcc if needed), forward with your own subject – with attachments from folders you allow (up to 25 MB per file, 50 MB and 20 files per message). With Thunderbird, the AI can also send a saved draft – only after you confirm and only if you have turned on direct sending yourself. With Thunderbird, the AI can also create templates and replace existing ones – they are never sent.
• Organize. Mark as read, star; create, rename and move folders; move, copy or trash messages.

With Thunderbird, also: the email you have selected, tags and the address book.

With Apple Mail: read, search, save attachments, prepare new messages, replies and forwards as drafts, mark, move, copy, put in the trash, create and rename folders – but no sending.

You stay in control

• Only the accounts you choose. The AI sees only the accounts you select – none at the start.
• Nothing is sent without you. The AI saves your message as a draft or opens it in Thunderbird, and you send it yourself. Only you can allow your AI to send directly. The Apple Mail edition does not send at all.
• Nothing is deleted for good. Deleting always means moving to the trash. Moving and deleting are off until you allow them.
• Local. MailBridge runs on your computer and opens no network port. The IMAP edition connects, encrypted, directly to your provider's mail server; your password is kept only in the macOS Keychain or the Windows Credential Manager. The Apple Mail edition needs the password of the mail server per account only for drafts with your own text; it is kept only in the macOS Keychain.

Download for free

Easiest way: copy the text for your edition into your AI app, for example a new chat in Claude Desktop. The AI then guides you step by step through download and setup.

Prefer to do it without AI? The steps at a glance

1. Install Node.js

   Free, version 20 or later (the “LTS” version). All editions need it for setup – even though Claude Desktop brings its own Node.js.

   Download Node.jsExternal site: nodejs.org
2. Install in your AI app

   In Claude Desktop: Settings › Extensions › Advanced settings › “Install Extension…”, choose the .mcpb file and confirm the installation. Other MCP apps you set up by hand (see the guide). For Thunderbird, also: Add-ons and Themes › gear icon › “Install Add-on From File…” with the .xpi file.

3. Set it up once

   Run one command in Terminal (Mac) or PowerShell (Windows). There you choose which accounts your AI may see and whether it may send directly (default: no); for IMAP you also enter your password here. With Apple Mail, macOS asks once whether Terminal or Claude may control the Mail app – please click “Allow”; for drafts with your own text you enter the password of the mail server per account. The command to copy is in the guide.

4. Restart

   Quit your AI app (and Thunderbird, if used) once and start it again – done.

For experts: checksums (SHA-256) to verify the downloaded files:
Thunderbird .mcpb 4803580cd3d1515174a5bea6737873c08fbac1d588add4a61a02747d44b194e6
Thunderbird .xpi f98b00858a87f78202ee3a4e00e83413d0c67aab39521ecc9b80f6c910ef396c
IMAP .mcpb bd3392ffcc3eefbbdf1c048b501032d0bc577abb500393aa88ed53d5ccff8ff5
Apple Mail .mcpb c089378f65d48b1aa1c0ec909720df069d1e05bb517191b01d145a0dba86a3bb

MailBridge is available only here, not in add-on stores or package registries. Free to use under the terms of use; please always download the files from this page so you get the current, unmodified version.

Requirements

• macOS or Windows 11 (Apple Mail: macOS only)
• An AI app with MCP support on the same computer, for example Claude Desktop
• Node.js version 20 or later (free)
• For Thunderbird: Thunderbird 128 or later – tested with Thunderbird 153 ESR on macOS and Thunderbird 156 on Windows
• For IMAP: an email account with IMAP access; with GMX and WEB.DE, IMAP must be switched on in the webmail settings; Gmail, iCloud Mail and Yahoo Mail need an app password
• For Apple Mail: a Mac with Apple Mail and at least one account set up in it – tested with macOS 27.0.1 and Mail 16.0; for drafts with your own text the password of the mail server (an app-specific password for iCloud and Google)

What leaves your computer – and what doesn't

MailBridge sends nothing to us: no usage tracking, no licence check, no error reports. Please note: whatever your AI app reads through MailBridge is processed under the rules of your AI provider – just like every question you ask it.

Questions

To kontakt@mcp-interfaces.com. Helpful: edition, tool name, exact error text and operating system.