protonmail-mcp-server

Crates.io	protonmail-mcp-server
lib.rs	protonmail-mcp-server
version	2026.1.25
created_at	2026-01-22 17:15:58.840599+00
updated_at	2026-01-25 14:03:16.528373+00
description	MCP server for IMAP email access via ProtonMail Bridge
homepage
repository	https://github.com/tensor-templar/protonmail-mcp-server
max_upload_size
id	2062233
size	173,095

Tensor Templar (TensorTemplar)

documentation

README

ProtonMail MCP Server

Unofficial IMAP-backed MCP (Model Context Protocol) server for ProtonMail Bridge. Exposes mailbox operations as MCP tools so AI assistants can list, search, and retrieve mail through a local Bridge connection.

Quickstart

Install

# From crates.io (recommended)
cargo install protonmail-mcp-server --features http

# Or from source
git clone https://github.com/tensor-templar/protonmail-mcp-server
cd protonmail-mcp-server
cargo install --path . --features http

Configure and Run

cp .env.example .env
# Edit .env with your IMAP and MCP settings
protonmail-mcp-server

HTTP Transport Deployment

Architecture

┌─────────────┐     HTTPS/SSE      ┌──────────────────┐     IMAP
│   Agent 1   │◄──────────────────►│                  │◄──────────►┌────────────────┐
├─────────────┤                    │   MCP Server     │            │ ProtonMail     │
│   Agent 2   │◄──────────────────►│   (HTTP+SSE)     │◄──────────►│ Bridge         │
├─────────────┤                    │                  │            │                │
│   Agent N   │◄──────────────────►│ Per-session IMAP │◄──────────►│ localhost:1143 │
└─────────────┘                    └──────────────────┘            └────────────────┘

Each MCP session gets its own IMAP connection
Bearer token authentication required
SSE (Server-Sent Events) for streaming responses

Configuration

Variable	Default	Description
`MCP_TRANSPORT`	`stdio`	Transport mode: `stdio` or `http`
`MCP_HTTP_BIND`	`127.0.0.1:8080`	HTTP server bind address
`MCP_AUTH_TOKEN`	(required for http)	Bearer token for authentication
`MCP_SSE_KEEPALIVE`	`true`	Enable SSE keep-alive pings (see note below)

Note: If using Python MCP SDK < 1.25.0, set MCP_SSE_KEEPALIVE=false to avoid JSON parsing errors. The older SDK can't handle empty SSE data fields sent as keep-alive pings. See: python-sdk#1672

Running HTTP Server

# Via environment
MCP_TRANSPORT=http MCP_AUTH_TOKEN=secret123 ./target/release/protonmail-mcp-server

# Via CLI override
./target/release/protonmail-mcp-server --transport http --bind 0.0.0.0:8080

Client Usage

# Initialize session
curl -X POST http://localhost:8080/mcp \
  -H "Authorization: Bearer secret123" \
  -H "Content-Type: application/json" \
  -H "Accept: application/json, text/event-stream" \
  -d '{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2024-11-05","capabilities":{},"clientInfo":{"name":"my-agent","version":"1.0"}}}'

Security Considerations

Network binding: Default 127.0.0.1 (localhost only). Use 0.0.0.0 for remote access.
Authentication: MCP_AUTH_TOKEN is mandatory for HTTP mode.
TLS: For production, deploy behind a reverse proxy (nginx, Caddy) with HTTPS.

Available MCP Tools

Tool	Description	Annotations
`list_mailboxes`	List available mailboxes	read-only
`search_emails`	Search emails with date filtering	read-only
`get_email`	Fetch full email content by ID	read-only
`get_current_date`	Get current UTC timestamp	read-only
`list_tags`	List available flags for a mailbox	read-only
`get_email_tags`	Get flags on a specific email	read-only
`apply_tag`	Apply a flag to an email	idempotent
`remove_tag`	Remove a flag from an email	destructive
`move_email`	Move email to another folder	destructive
`get_attachment`	Download attachment (file or base64)	destructive, open-world