stratomcp

title: stratomcp description: Local MCP server for searching and managing a Strato mailbox with Claude

Related MCP server: email-mcp

Search your Strato mailbox with Claude

stratomcp connects Claude to your Strato mailbox. Ask questions about your email, find messages, or get help writing replies. You choose whether Claude can only read mail, organize it, or also send it.

It runs on your Mac as a Model Context Protocol (MCP) server. Your password stays in macOS Keychain.

What you can do

• Find emails by sender, date, topic, or invoice number

• Summarize conversations and read attachments you approve

• Check folders and unread messages

• Save drafts, organize mail, or send replies when you enable those permissions

Quick setup

What you need

• macOS

• A Strato mailbox and its mailbox password

• Node.js 22.13 or newer

• Claude Desktop, Claude Code, or both

Install

1. Download and unzip this repository.

2. Double-click Setup.command.

3. Enter your mailbox details when prompted.

4. Choose a permission mode and a folder for attachments.

5. Let setup connect to Claude Desktop, Claude Code, or both.

6. Restart Claude Desktop or open a new Claude Code session.

Not sure what to choose? Keep Read-only mailbox and the suggested download folder. You can change both later.

Setup stores your password in Keychain, tests the connection, and offers to build a local search index. The first index build can take several minutes; later updates happen automatically. Claude Code users can also install optional mail helper agents for searching and summarizing.

The application is installed in ~/Library/Application Support/stratomcp/app. No configuration-file editing is needed for a single mailbox.

Try it

After setup, ask Claude:

• "Which mail folders do I have?"

• "Find the latest invoice from my internet provider."

• "Summarize the open points in the thread with the landlord."

• "Suggest a reply to the latest message, but do not send it."

In read-only mode, suggested replies stay in the conversation. Saving one in your mailbox requires Organize and draft or Full access.

Choose what Claude can do

Setup asks you to choose a mode for each mailbox:

Local indexing and approved attachment downloads work in every mode. Enabling sending requires typing yes during setup. The server enforces your choice; an email or a tool call cannot grant extra permissions.

Changing permissions

For the standard installation, open Terminal and run:

cd "$HOME/Library/Application Support/stratomcp/app"
npm run setup -- --permissions

If you installed from a clone, run the command in that folder instead. Choose a new mode or press Return to keep the current one.

This changes only permissions, not your password, download folder, or client setup. The next tool call uses the new mode; work already running is not cancelled. Ask Claude to list your accounts to check the current modes.

Attachments

Claude sees attachment names and sizes before downloading them. Review its request before approving a download.

During setup, choose where downloads go. Press Return to keep the suggested folder (~/Downloads/stratomcp for a new installation), or enter a full path. ~ means your home folder, so you can enter a path such as ~/Documents/Mail attachments.

Want downloads next to a cloned application? For an app at ~/Claude/MCP/strato-mcp, choose ~/Claude/MCP/strato-mcp-downloads. Setup rejects folders inside the application because updates replace those files.

To change the folder later, open Terminal and run:

cd "$HOME/Library/Application Support/stratomcp/app"
npm run setup

Keep your existing mailbox settings when prompted. Your choice applies to both Claude clients. Existing downloads are not moved. For a clone, use its folder instead of the installed path above.

• Claude cannot choose a different folder through a download tool call.

• Existing files are never overwritten.

• Text-like attachments can be returned directly to Claude.

• The default download limit is 25 MB; larger attachments remain supported.

• Downloading a file does not make it safe to open or run.

Safety model

An email can contain instructions designed to trick an AI assistant. This is called prompt injection. stratomcp labels email content, attachment names, and external error details as untrusted data, not instructions.

These safeguards reduce risk; they do not make prompt injection impossible. Keep Claude's approval prompts enabled. Check recipients and content before sending, and never approve an action only because an email asks for it.

Read-only mode blocks mailbox changes, including marking messages as read. The modes do not control other tools you give Claude, such as shell or browser access.

See SECURITY.md to report a security concern privately.

Privacy

Your password stays in Keychain. Settings and the search index stay on your Mac. stratomcp does not upload the whole index, but mail and attachment content returned to Claude are shared with the AI provider as part of your conversation.

The index covers the last three years, excluding Spam and Trash. It contains message text and attachment names, not attachment contents. Claude can search older or excluded mail directly. The index refreshes automatically while the server runs.

Use FileVault if your Mac may store sensitive mail.

Update

Download and unzip the new version, then run its Setup.command. Keep your existing settings when prompted, then restart Claude. Account settings, Keychain passwords, the index, and downloads outside the application folder are preserved.

Troubleshooting

Advanced configuration

Most users can use setup without editing files. The options below are for manual configuration and development.

Install from a clone

npm install
npm run setup

This uses the current checkout instead of copying the application elsewhere.

Account settings and multiple mailboxes

The settings file is ~/.config/stratomcp/accounts.json. A new account looks like:

{
  "accounts": [
    {
      "name": "main",
      "email": "user@example.com",
      "displayName": "Example User",
      "accessMode": "read-only",
      "allowSend": false
    }
  ]
}

For another mailbox, add another object to accounts with a different name and email, then rerun setup. Choose to keep the existing mailbox settings. Setup checks each account and lets you choose its permissions.

• accessMode is read-only, organize, or full. Invalid values are rejected.

• It takes precedence over allowSend; setup keeps that older field in sync.

• Older accounts without accessMode retain their behavior: allowSend: true means full access; false or omitted means organize and draft.

• The top-level attachmentDir stores the download folder as an absolute path.

Tools remain listed for all accounts, but disallowed actions are rejected by the server for the account used in each call.

Environment variables

For example, the password variable for an account named main is STRATOMCP_PASSWORD_MAIN.

Use an absolute path for STRATOMCP_ATTACHMENT_DIR and restart the server after changing it. A literal ~ in an environment value is not expanded; relative paths resolve against the server's working directory.

Download and error-handling details

The download folder is selected in this order: STRATOMCP_ATTACHMENT_DIR, the saved attachmentDir, then ~/Downloads/stratomcp. The former dir tool argument is rejected; remove it from old saved tool calls.

New download directories use 0700 permissions and files use 0600. Existing directory permissions are unchanged. Use a dedicated folder, not a startup or application configuration folder. Symlinks in the configured path are followed; this is not a sandbox against other local processes.

Tool-handler errors separate server messages from untrustedDetails and include a security notice. Sender-provided filenames are preserved in those details.

Index maintenance and connection defaults

Run an index refresh manually:

cd "$HOME/Library/Application Support/stratomcp/app"
npm run sync

Index a different time window:

node src/sync.js --years 5

The server uses Strato's secure defaults:

• IMAP at imap.strato.de:993

• SMTP at smtp.strato.de:465

• IMAP4rev2 disabled because Strato can return empty search results when it is enabled

• Sent messages appended to the Sent folder because SMTP does not store a copy

Other providers may work when the host settings are overridden, but they are not tested.

Available tools

Uninstall

Remove the Claude Code registration if it was installed:

claude mcp remove strato

Remove the installed application, settings, index, and Keychain password:

rm -rf "$HOME/Library/Application Support/stratomcp"
rm -rf "$HOME/.config/stratomcp"
security delete-generic-password -s stratomcp -a user@example.com

Replace user@example.com with your mailbox address. For Claude Desktop, remove the strato entry from mcpServers in ~/Library/Application Support/Claude/claude_desktop_config.json, then restart the app.