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Proton Mail Bridge Client

by googlarz

Local Proton Mail access through Bridge with MCP tools and CLI workflows for searching, drafting, sending, triage, and attachments.

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Install Proton Mail Bridge Client

Pick your client, then add it in one click or paste the config.

STDIONode.js
~/Library/Application Support/Claude/claude_desktop_config.json
claude_desktop_config.json
{
  "mcpServers": {
    "googlarz-proton-mail-bridge-client": {
      "command": "npx",
      "args": [
        "-y",
        "proton-mail-bridge-client"
      ],
      "env": {
        "PROTONMAIL_MODE": "YOUR_VALUE_HERE",
        "PROTONMAIL_READ_ONLY": "YOUR_VALUE_HERE",
        "PROTONMAIL_TOOL_TIER": "YOUR_VALUE_HERE"
      }
    }
  }
}

Settings → Developer → Edit Config, merge this into mcpServers, then fully quit and reopen Claude Desktop.

Values are written into the snippet above so you can paste it as is. They never leave your browser.

Install not yet sandbox-tested— we haven't run this command through our automated sandbox yet. Not a red flag; we're working through the catalog.

Overview

googlarz/proton-mail-bridge-client connects MCP clients and its CLI to Proton Mail through a locally running Proton Mail Bridge instance. It supports mailbox search, reading, drafting, sending, thread triage, folder management, attachment handling, calendar invitations, and multiple isolated accounts. A local SQLite index enables full-text search, while safety modes control whether actions are read-only, draft-only, assisted, or fully enabled. Reach for it when an agent or script needs to work with Proton Mail without using a third-party mail relay.

Use cases

  • Search a local Proton Mail index for messages and attachments
  • Draft replies for review without sending them
  • Triage, archive, move, or batch-process email threads
  • Run Proton Mail workflows from scripts, cron jobs, or pipelines
  • Answer calendar invitations from an MCP client

Key features

  • Proton Mail access through local Proton Mail Bridge
  • 116 MCP tools with a 25-tool core tier
  • Local SQLite full-text mailbox index
  • Multiple isolated Proton accounts
  • Configurable read-only, draft, assisted, and full modes
  • CLI support for scripting and diagnostics

Tools1

What Proton Mail Bridge Client lets your agent do. Expand a tool for its parameters.

Self-reported~20 tokens of context

Security & health

What it can reach and how reliably it runs — from our own checks, not the maintainer’s claims.

ActiveLast checked Today

Recent health check succeeded.

Supply-chain signal

No high-severity advisories surfaced by our automated scan.

Critical 0High 0Medium 0Low 0

Scanned 5d ago via OSV.dev · proton-mail-bridge-client (npm)

Adoption & maintenance

Factual signals from GitHub, npm, and our automated checks — not a rating.

GitHub stars83Stargazers on the source repository.
npm downloads6kPackage downloads in the last 30 days.
Last commit2d agoMost recent push to the default branch.
Tools exposed1Callable tools this server registers over MCP.

How Proton Mail Bridge Client works

What googlarz/proton-mail-bridge-client does

googlarz/proton-mail-bridge-client adds an MCP and command-line interface for Proton Mail accounts exposed by Proton Mail Bridge. It covers common mailbox workflows, including searching and reading messages, preparing and sending mail, managing drafts, triaging threads, moving or archiving messages, handling folders, saving attachments, and responding to calendar invitations. The server also exposes list_remote_drafts, which lists the primary account's remote Proton Drafts folder.

A local SQLite index supports full-text mailbox search and tracks read state with the server. Multiple Proton logins or Bridge-exposed addresses can be configured as separate accounts, each with its own index, drafts, and settings. The project includes 116 MCP tools in its full tier and a 25-tool core tier.

How it works

Proton Mail Bridge must be installed, signed in, and running. The bridge decrypts mail locally and provides the IMAP and SMTP access used by this project; the server does not replace Bridge or connect directly to Proton's remote service. Mail follows a local path from Proton Mail to Bridge, then to the server and the selected AI client.

Claude Desktop, Cline, or another MCP client can invoke the server's mail operations. The same capabilities are available through a CLI for scripts, scheduled jobs, pipelines, diagnostics, and automation without Claude. A doctor command checks configured accounts, while report produces a diagnostic summary.

Safety behavior is configurable. PROTONMAIL_MODE provides read-only, drafts, assisted, and full presets; draft mode allows reading, searching, and preparing drafts while blocking sending and deletion. Read-only mode prevents mailbox changes, and additional controls include send gating, destructive-action confirmation, and per-action allowlists.

Setup and configuration

Install Proton Mail Bridge and copy its generated Bridge password from the Bridge application. This password is separate from the Proton account password. Node.js 24 or later is required for the npm installation and the bundled setup flow.

For Claude Desktop, users can open a platform-specific MCP bundle or install the npm package globally and run proton-mail-bridge-client setup-claude-desktop. The setup process can check Bridge ports and write the client configuration. Supported bundle targets include macOS Apple silicon and Intel, Linux x64 and ARM64, and Windows x64. After changing the Claude Desktop configuration, fully quit and reopen the application.

Optional settings cover Bridge IMAP and SMTP host or port, read-only operation, sending permissions, signatures, additional accounts, data and download directories, and the selected tool tier. The documented environment controls include PROTONMAIL_MODE, PROTONMAIL_READ_ONLY, and PROTONMAIL_TOOL_TIER.

Tools and capabilities

  • Search a local index across the mailbox.
  • Read, draft, send, reply to, archive, move, and triage messages and threads.
  • Batch-act on threads and manage folders.
  • Find and save attachments, including PDF text and pictures.
  • Answer calendar invitations.
  • List remote drafts for the primary account.
  • Run mailbox rules that can propose filters and cleanup, preview changes, and forward by condition.
  • Configure per-account autoresponders with previews, approval drafts, and working hours.
  • Use the CLI directly, including a generic tool passthrough and commands for diagnostics.

Limitations and notes

Bridge must remain installed, signed in, and running for mailbox access. The server communicates with Bridge over local IMAP and SMTP on the machine where it runs. Email content requested by an AI client is visible to that client; when Claude Desktop uses Anthropic's hosted API, conversation content can be sent to Anthropic under its privacy policy. A self-hosted or local-only model can keep that content on the machine.

Sending is not automatically enabled by every safety configuration. Draft and read-only modes are intended for review or browsing, and automatic replies are off by default. The local index and account data are maintained separately for each configured account.

Read the full README View source on GitHub

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Frequently Asked Questions about Proton Mail Bridge Client

googlarz/proton-mail-bridge-client is an MCP server that connects AI clients and CLI workflows to Proton Mail through a local Proton Mail Bridge instance. Its main tools support searching, reading, drafting, sending, triaging threads, handling attachments, managing folders, and listing remote drafts, with configurable safety modes.

Install Proton Mail Bridge first, then install the npm package globally with `npm install -g proton-mail-bridge-client` and run `proton-mail-bridge-client setup-claude-desktop`. Alternatively, open the platform-specific MCP bundle from the latest release. Node.js 24 or later is required.

Yes, it can work with Cursor because it supports MCP clients, although the quick-start instructions specifically describe Claude Desktop and Cline. Proton Mail Bridge must be installed, signed in, and running, and the MCP client must be configured to launch the server.

Set `PROTONMAIL_MODE=drafts` to allow reading, searching, and draft preparation without sending or deleting messages. For browsing without mailbox changes, set `PROTONMAIL_READ_ONLY=true`. The server also supports send gates, destructive-action confirmations, and per-action allowlists.

Yes, it supports multiple accounts, with each Proton login or Bridge-exposed address isolated with its own index, drafts, and settings. Additional accounts can be supplied during setup, while Bridge remains the local gateway for each configured mailbox.

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