mail-imap-mcp-rs

A secure, efficient Model Context Protocol (MCP) server for IMAP email access over stdio by default, with optional streamable HTTP transport. Provides read/write operations on IMAP mailboxes with structured output, cursor-based pagination, and security-first design.

Features

• Secure by default: TLS-only connections, password secrets never logged or returned
• Structured output: Consistent tool response envelope with summaries and metadata
• Cursor-based pagination: Efficient message searching across large mailboxes
• Message parsing: Extract text, HTML, headers, and attachments with sanitization
• Multi-account support: Configure multiple IMAP accounts via environment variables
• PDF text extraction: Optional text extraction from PDF attachments
• Rust-powered: Fast, memory-safe async/await implementation with tokio
• Write operations: Message mutations and mailbox management require explicit enable

Installation

Choose an installation method based on your environment and preferences.

Using NPX (Recommended)

Easiest method - no global install required.

npx @bradsjm/mail-imap-mcp-rs@latest

Optional HTTP transport example:

npx @bradsjm/mail-imap-mcp-rs@latest --transport http

Supported npm/native targets:

• macOS: Apple Silicon (aarch64-apple-darwin), Intel (x86_64-apple-darwin)
• Linux arm64: glibc (aarch64-unknown-linux-gnu)
• Linux x64: glibc (x86_64-unknown-linux-gnu), musl/Alpine (x86_64-unknown-linux-musl)
• Windows x64: MSVC (x86_64-pc-windows-msvc)

Or install globally:

npm install -g @bradsjm/mail-imap-mcp-rs
mail-imap-mcp-rs

Using Curl Installer (Linux/macOS)

Install a pinned release directly from GitHub Releases:

curl --proto '=https' --tlsv1.2 -LsSf https://github.com/bradsjm/mail-imap-mcp-rs/releases/download/v0.1.0/mail-imap-mcp-rs-installer.sh | sh

Safer alternative (download, inspect, then run):

curl --proto '=https' --tlsv1.2 -LsSf -o mail-imap-mcp-rs-installer.sh https://github.com/bradsjm/mail-imap-mcp-rs/releases/download/v0.1.0/mail-imap-mcp-rs-installer.sh
sh mail-imap-mcp-rs-installer.sh

Using Docker

Pull prebuilt multi-arch image from GHCR:

docker pull ghcr.io/bradsjm/mail-imap-mcp-rs:latest
docker run --rm -i --env-file .env ghcr.io/bradsjm/mail-imap-mcp-rs:latest

Optional HTTP transport example:

docker run --rm -p 127.0.0.1:8000:8000 --env-file .env ghcr.io/bradsjm/mail-imap-mcp-rs:latest --transport http

Build locally:

docker build -t mail-imap-mcp-rs .
docker run --rm -i --env-file .env mail-imap-mcp-rs

From Source

cargo install --path .

Binary available at $HOME/.cargo/mail-imap-mcp-rs.

Transport Modes

The server defaults to stdio, which is the right mode for most MCP desktop integrations.

Use streamable HTTP only when you explicitly need it:

mail-imap-mcp-rs --transport http

Optional bind controls:

mail-imap-mcp-rs --transport http --http-bind-address 127.0.0.1 --http-port 8000

HTTP mode serves MCP at http://127.0.0.1:8000/mcp by default.

Security note:

• The HTTP transport defaults to localhost only.
• The server does not add built-in HTTP authentication or TLS termination.
• Do not leave this server publicly reachable unless exposure is intentional and protected by a trusted boundary such as a reverse proxy, firewall, or private network.

Quick Start

Configure MCP

Use this example MCP configuration and add your credentials:

{
  "mcpServers": {
    "server-name": {
      "command": "npx",
      "args": ["-y", "@bradsjm/mail-imap-mcp-rs@latest"],
      "env": {
        "MAIL_IMAP_DEFAULT_HOST": "imap.gmail.com",
        "MAIL_IMAP_DEFAULT_USER": "[email protected]",
        "MAIL_IMAP_DEFAULT_PASS": "your-app-password"
      }
    }
  }
}

# Optional: defaults shown
MAIL_IMAP_DEFAULT_PORT=993
MAIL_IMAP_DEFAULT_SECURE=true

Important: Use an app-specific password, not your account password. See your email provider's documentation for generating app passwords.

Enabling Write Operations

By default, write operations (message mutations and mailbox management) are disabled. Enable explicitly:

MAIL_IMAP_WRITE_ENABLED=true

Multiple Accounts

# Default account
MAIL_IMAP_DEFAULT_HOST=imap.gmail.com
[email protected]
MAIL_IMAP_DEFAULT_PASS=app-password

# Work account
MAIL_IMAP_WORK_HOST=outlook.office365.com
[email protected]
MAIL_IMAP_WORK_PASS=work-password

# Personal account
MAIL_IMAP_PERSONAL_HOST=imap.fastmail.com
[email protected]
MAIL_IMAP_PERSONAL_PASS=personal-password

Advanced Configuration

For timeouts, cursor settings, read-session cache tuning, and other advanced options, see Advanced Configuration.

To trust a private or self-signed IMAP server certificate without disabling TLS verification, set:

MAIL_IMAP_CA_CERT_PATH=/path/to/ca-certificates.pem

Tool Reference

All tools return a consistent envelope:

{
  "summary": "Human-readable outcome",
  "data": { /* tool-specific data */ },
  "meta": {
    "now_utc": "2024-02-26T10:30:45.123Z",
    "duration_ms": 245
  }
}

Read Operations

| Tool | Purpose | |------|---------| | imap_list_accounts | List configured accounts without exposing credentials | | imap_list_mailboxes | List all visible mailboxes/folders | | imap_search_messages | Search with cursor-based pagination | | imap_get_message | Get parsed message details | | imap_get_message_raw | Get RFC822 source for diagnostics |

Write Operations

| Tool | Purpose | |------|---------| | imap_apply_to_messages | Apply one action (move, copy, delete) to explicit messages | | imap_update_message_flags | Add, remove, or replace flags on explicit messages | | imap_manage_mailbox | Create, rename, or delete a mailbox | | imap_get_operation | Poll a write operation until it reaches a terminal state | | imap_cancel_operation | Request cancellation for a running write operation |

Write operations require MAIL_IMAP_WRITE_ENABLED=true.

For complete tool contracts, input/output schemas, and validation rules, see Tool Contract.

Troubleshooting

Connection Timeout

Error: operation timed out: tcp connect timeout

Increase MAIL_IMAP_CONNECT_TIMEOUT_MS (default: 30,000 ms). See Advanced Configuration.

Authentication Failed

Error: authentication failed: [AUTHENTICATIONFAILED] Authentication failed.

• Verify username and password are correct
• Use an app-specific password (not account password) for Gmail/Outlook
• Check account allows IMAP access

Write Operations Disabled

Error: invalid input: write tools are disabled; set MAIL_IMAP_WRITE_ENABLED=true

Set MAIL_IMAP_WRITE_ENABLED=true to enable message mutation and mailbox management operations.

Cursor Invalid/Expired

Error: invalid input: cursor is invalid or expired

Rerun the search without a cursor. See Cursor Pagination for details.

Search Too Broad

Error: invalid input: search matched 25000 messages; narrow filters to at most 1000 results

Add tighter filters (last_days, from, subject, date ranges) and rerun.

Mailbox Snapshot Changed

Error: conflict: mailbox snapshot changed; rerun search

The mailbox's UIDVALIDITY changed. Rerun search. See Message ID Format.

Security

For comprehensive security documentation, see Security Considerations.

Key security features:

• TLS enforcement: Insecure connections rejected
• Local HTTP default: Optional HTTP transport binds to localhost unless you override it
• Password secrecy: Passwords never logged or returned
• Bounded outputs: Body text, HTML, attachments truncated to limits
• Write gating: Destructive operations require explicit opt-in
• HTML sanitization: HTML sanitized using ammonia

Documentation

• Tool Contract - Complete tool definitions, input/output schemas, validation rules
• Message ID Format - Stable message identifier format and behavior
• Cursor Pagination - Pagination behavior, expiration, error handling
• Security Considerations - Security features, best practices, limitations
• Advanced Configuration - Timeouts, cursors, performance tuning

License

MIT License - see LICENSE file for details.

Contributing

Contributions welcome! Ensure code is formatted, linted, and tested before submitting.

Acknowledgement

Code and documentation in this repository was AI assisted using OpenCode with various models including GPT-5 models from OpenAI.