Gmail AutoAuth MCP Server (Actively Maintained Fork)

This is an actively maintained fork of GongRzhe/Gmail-MCP-Server.

The original repository has been unmaintained since August 2025 — 7+ months with zero maintainer activity and 72+ unmerged pull requests. I use this MCP server daily as part of my Claude Code workflow and depend on it working correctly, so I picked it up.

Pull requests are welcome. If you've been sitting on fixes or features with nowhere to submit them, this is the place.

What this fork adds

• Fixed reply threading — auto-resolves In-Reply-To and References headers so email replies land in the correct thread instead of creating orphaned messages (upstream PR #91, still pending)
• Send-as alias support — optional from parameter for multi-identity email management (send from any configured Gmail alias)
• Reply-all tool — reply_all automatically fetches the original email, builds To/CC recipient lists (excluding yourself), and sets proper threading headers (PR #3 by @MaxGhenis)
• Fixed list_filters — was returning empty array due to wrong response property name (PR #4 by @nicholas-anthony-ai)
• Custom OAuth2 scoping — --scopes flag to request only the permissions you need, with automatic tool filtering (PR #6 by @tansanDOTeth)
• CI/CD hardening — fixed shell injection vector in GitHub Actions workflow, added least-privilege permissions scope (PR #9 by @JF10R)
• Security hardening — fixed path traversal in attachment download, restricted OAuth credential file permissions (PR #10 by @JF10R)
• Dependency security — upgraded MCP SDK to v1.27.1 (3 CVE fixes), upgraded nodemailer (DoS + routing fix), moved dev-only packages out of production deps (PR #11 by @JF10R)

All features are production-tested in daily use.

---

A Model Context Protocol (MCP) server for Gmail integration in Claude Desktop with auto authentication support. This server enables AI assistants to manage Gmail through natural language interactions.

Features

• Send emails with subject, content, attachments, and recipients
• Full attachment support - send and receive file attachments
• Download email attachments to local filesystem
• Support for HTML emails and multipart messages with both HTML and plain text versions
• Full support for international characters in subject lines and email content
• Read email messages by ID with advanced MIME structure handling
• Enhanced attachment display showing filenames, types, sizes, and download IDs
• Search emails with various criteria (subject, sender, date range)
• Comprehensive label management with ability to create, update, delete and list labels
• List all available Gmail labels (system and user-defined)
• List emails in inbox, sent, or custom labels
• Mark emails as read/unread
• Move emails to different labels/folders
• Delete emails
• Batch operations for efficiently processing multiple emails at once
• Full integration with Gmail API
• Simple OAuth2 authentication flow with auto browser launch
• Support for both Desktop and Web application credentials
• Global credential storage for convenience

Installation & Authentication

Installing Manually

1. Create a Google Cloud Project and obtain credentials:

   a. Create a Google Cloud Project:

   • Go to Google Cloud Console
   • Create a new project or select an existing one
   • Enable the Gmail API for your project

   b. Create OAuth 2.0 Credentials:

   • Go to "APIs & Services" > "Credentials"
   • Click "Create Credentials" > "OAuth client ID"
   • Choose either "Desktop app" or "Web application" as application type
   • Give it a name and click "Create"
   • For Web application, add http://localhost:3000/oauth2callback to the authorized redirect URIs
   • Download the JSON file of your client's OAuth keys
   • Rename the key file to gcp-oauth.keys.json

2. Run Authentication:

   You can authenticate in two ways:

   a. Global Authentication (Recommended):

   # First time: Place gcp-oauth.keys.json in your home directory's .gmail-mcp folder
   mkdir -p ~/.gmail-mcp
   mv gcp-oauth.keys.json ~/.gmail-mcp/
   
   # Run authentication from anywhere
   npx @gongrzhe/server-gmail-autoauth-mcp auth
   

   b. Local Authentication:

   # Place gcp-oauth.keys.json in your current directory
   # The file will be automatically copied to global config
   npx @gongrzhe/server-gmail-autoauth-mcp auth
   

   The authentication process will:

   • Look for gcp-oauth.keys.json in the current directory or ~/.gmail-mcp/
   • If found in current directory, copy it to ~/.gmail-mcp/
   • Open your default browser for Google authentication
   • Save credentials as ~/.gmail-mcp/credentials.json

   Note:

   • After successful authentication, credentials are stored globally in ~/.gmail-mcp/ and can be used from any directory
   • Both Desktop app and Web application credentials are supported
   • For Web application credentials, make sure to add http://localhost:3000/oauth2callback to your authorized redirect URIs

3. Configure in Claude Desktop:

{
  "mcpServers": {
    "gmail": {
      "command": "npx",
      "args": [
        "@gongrzhe/server-gmail-autoauth-mcp"
      ]
    }
  }
}

Docker Support

If you prefer using Docker:

1. Authentication:

docker run -i --rm \
  --mount type=bind,source=/path/to/gcp-oauth.keys.json,target=/gcp-oauth.keys.json \
  -v mcp-gmail:/gmail-server \
  -e GMAIL_OAUTH_PATH=/gcp-oauth.keys.json \
  -e "GMAIL_CREDENTIALS_PATH=/gmail-server/credentials.json" \
  -p 3000:3000 \
  mcp/gmail auth

2. Usage:

{
  "mcpServers": {
    "gmail": {
      "command": "docker",
      "args": [
        "run",
        "-i",
        "--rm",
        "-v",
        "mcp-gmail:/gmail-server",
        "-e",
        "GMAIL_CREDENTIALS_PATH=/gmail-server/credentials.json",
        "mcp/gmail"
      ]
    }
  }
}

Cloud Server Authentication

For cloud server environments (like n8n), you can specify a custom callback URL during authentication:

npx @gongrzhe/server-gmail-autoauth-mcp auth https://gmail.gongrzhe.com/oauth2callback

Setup Instructions for Cloud Environment

1. Configure Reverse Proxy:

   • Set up your n8n container to expose a port for authentication
   • Configure a reverse proxy to forward traffic from your domain (e.g., gmail.gongrzhe.com) to this port

2. DNS Configuration:

   • Add an A record in your DNS settings to resolve your domain to your cloud server's IP address

3. Google Cloud Platform Setup:

   • In your Google Cloud Console, add your custom domain callback URL (e.g., https://gmail.gongrzhe.com/oauth2callback) to the authorized redirect URIs list

4. Run Authentication:

   npx @gongrzhe/server-gmail-autoauth-mcp auth https://gmail.gongrzhe.com/oauth2callback
   

5. Configure in your application:

   {
     "mcpServers": {
       "gmail": {
         "command": "npx",
         "args": [
           "@gongrzhe/server-gmail-autoauth-mcp"
         ]
       }
     }
   }
   

This approach allows authentication flows to work properly in environments where localhost isn't accessible, such as containerized applications or cloud servers.

OAuth Scopes

You can limit the server's Gmail access by specifying OAuth scopes during authentication. This controls which tools are available to the LLM, reducing the attack surface for sensitive operations.

Available Scopes

Scope	Description
gmail.readonly	Read-only access to emails (search, read, download attachments)
gmail.modify	Full read/write access to emails (superset of readonly - includes sending, modifying, deleting)
gmail.compose	Create drafts and send emails only
gmail.send	Send emails only
gmail.labels	Manage labels only
gmail.settings.basic	Manage filters and settings

Note: gmail.modify is a superset that includes all read capabilities. You don't need gmail.readonly if you have gmail.modify.

Authenticating with Specific Scopes

Use the --scopes flag to request only the permissions you need:

# Read-only access (recommended for safe browsing)
npx @gongrzhe/server-gmail-autoauth-mcp auth --scopes=gmail.readonly

# Read-only with filter management
npx @gongrzhe/server-gmail-autoauth-mcp auth --scopes=gmail.readonly,gmail.settings.basic

# Full access (default behavior)
npx @gongrzhe/server-gmail-autoauth-mcp auth --scopes=gmail.modify,gmail.settings.basic

If no --scopes flag is provided, the server defaults to gmail.modify,gmail.settings.basic for full functionality.

Scope-to-Tool Mapping

The server automatically filters available tools based on your authorized scopes:

Tools	Required Scope (any)
read_email, search_emails, download_attachment	gmail.readonly or gmail.modify
list_email_labels	gmail.readonly, gmail.modify, or gmail.labels
send_email, draft_email, reply_all	gmail.modify, gmail.compose, or gmail.send
modify_email, delete_email, batch_modify_emails, batch_delete_emails	gmail.modify
create_label, update_label, delete_label, get_or_create_label	gmail.modify or gmail.labels
list_filters, get_filter, create_filter, delete_filter, create_filter_from_template	gmail.settings.basic

Re-authenticating

To change your scopes, simply run the auth command again with different scopes. This will replace your existing credentials.

Claude Code CLI Configuration

To use this MCP server with Claude Code, add it to your MCP settings.

Read-Only Configuration (Recommended for Safe Browsing)

First, authenticate with read-only scope:

npx @gongrzhe/server-gmail-autoauth-mcp auth --scopes=gmail.readonly

Then add to your Claude Code MCP settings (~/.claude/mcp_settings.json or project-level .mcp.json):

{
  "mcpServers": {
    "gmail": {
      "command": "npx",
      "args": ["@gongrzhe/server-gmail-autoauth-mcp"]
    }
  }
}

With read-only scopes, only these 4 tools will be available to Claude:

• read_email - Read email content
• search_emails - Search your inbox
• list_email_labels - List available labels
• download_attachment - Download attachments

Full Access Configuration

For full Gmail management capabilities:

npx @gongrzhe/server-gmail-autoauth-mcp auth --scopes=gmail.modify,gmail.settings.basic

{
  "mcpServers": {
    "gmail": {
      "command": "npx",
      "args": ["@gongrzhe/server-gmail-autoauth-mcp"]
    }
  }
}

This enables all 20 tools including sending emails, managing labels, creating filters, reply-all, and batch operations.

Available Tools

The server provides the following tools that can be used through Claude Desktop:

1. Send Email (send_email)

Sends a new email immediately. Supports plain text, HTML, or multipart emails with optional file attachments.

Basic Email:

{
  "to": ["recipient@example.com"],
  "subject": "Meeting Tomorrow",
  "body": "Hi,\n\nJust a reminder about our meeting tomorrow at 10 AM.\n\nBest regards",
  "cc": ["cc@example.com"],
  "bcc": ["bcc@example.com"],
  "mimeType": "text/plain"
}

Email with Attachments:

{
  "to": ["recipient@example.com"],
  "subject": "Project Files",
  "body": "Hi,\n\nPlease find the project files attached.\n\nBest regards",
  "attachments": [
    "/path/to/document.pdf",
    "/path/to/spreadsheet.xlsx",
    "/path/to/presentation.pptx"
  ]
}

HTML Email Example:

{
  "to": ["recipient@example.com"],
  "subject": "Meeting Tomorrow",
  "mimeType": "text/html",
  "body": "Meeting ReminderJust a reminder about our meeting tomorrow at 10 AM.
Best regards
"
}

Multipart Email Example (HTML + Plain Text):

{
  "to": ["recipient@example.com"],
  "subject": "Meeting Tomorrow",
  "mimeType": "multipart/alternative",
  "body": "Hi,\n\nJust a reminder about our meeting tomorrow at 10 AM.\n\nBest regards",
  "htmlBody": "Meeting ReminderJust a reminder about our meeting tomorrow at 10 AM.
Best regards
"
}

2. Draft Email (draft_email)

Creates a draft email without sending it. Also supports attachments.

{
  "to": ["recipient@example.com"],
  "subject": "Draft Report",
  "body": "Here's the draft report for your review.",
  "cc": ["manager@example.com"],
  "attachments": ["/path/to/draft_report.docx"]
}

3. Read Email (read_email)

Retrieves the content of a specific email by its ID. Now shows enhanced attachment information.

{
  "messageId": "182ab45cd67ef"
}

Enhanced Response includes attachment details:

Subject: Project Files
From: sender@example.com
To: recipient@example.com
Date: Thu, 19 Jun 2025 10:30:00 -0400

Email body content here...

Attachments (2):
- document.pdf (application/pdf, 245 KB, ID: ANGjdJ9fkTs-i3GCQo5o97f_itG...)
- spreadsheet.xlsx (application/vnd.openxmlformats-officedocument.spreadsheetml.sheet, 89 KB, ID: BWHkeL8gkUt-j4HDRp6o98g_juI...)

4. Download Attachment (download_attachment)

NEW: Downloads email attachments to your local filesystem.

{
  "messageId": "182ab45cd67ef",
  "attachmentId": "ANGjdJ9fkTs-i3GCQo5o97f_itG...",
  "savePath": "/path/to/downloads",
  "filename": "downloaded_document.pdf"
}

Parameters:

• messageId: The ID of the email containing the attachment
• attachmentId: The attachment ID (shown in enhanced email display)
• savePath: Directory to save the file (optional, defaults to current directory)
• filename: Custom filename (optional, uses original filename if not provided)

5. Search Emails (search_emails)

Searches for emails using Gmail search syntax.

{
  "query": "from:sender@example.com after:2024/01/01 has:attachment",
  "maxResults": 10
}

6. Modify Email (modify_email)

Adds or removes labels from emails (move to different folders, archive, etc.).

{
  "messageId": "182ab45cd67ef",
  "addLabelIds": ["IMPORTANT"],
  "removeLabelIds": ["INBOX"]
}

7. Delete Email (delete_email)

Permanently deletes an email.

{
  "messageId": "182ab45cd67ef"
}

8. List Email Labels (list_email_labels)

Retrieves all available Gmail labels.

{}

9. Create Label (create_label)

Creates a new Gmail label.

{
  "name": "Important Projects",
  "messageListVisibility": "show",
  "labelListVisibility": "labelShow"
}

10. Update Label (update_label)

Updates an existing Gmail label.

{
  "id": "Label_1234567890",
  "name": "Urgent Projects",
  "messageListVisibility": "show",
  "labelListVisibility": "labelShow"
}

11. Delete Label (delete_label)

Deletes a Gmail label.

{
  "id": "Label_1234567890"
}

12. Get or Create Label (get_or_create_label)

Gets an existing label by name or creates it if it doesn't exist.

{
  "name": "Project XYZ",
  "messageListVisibility": "show",
  "labelListVisibility": "labelShow"
}

13. Batch Modify Emails (batch_modify_emails)

Modifies labels for multiple emails in efficient batches.

{
  "messageIds": ["182ab45cd67ef", "182ab45cd67eg", "182ab45cd67eh"],
  "addLabelIds": ["IMPORTANT"],
  "removeLabelIds": ["INBOX"],
  "batchSize": 50
}

14. Batch Delete Emails (batch_delete_emails)

Permanently deletes multiple emails in efficient batches.

{
  "messageIds": ["182ab45cd67ef", "182ab45cd67eg", "182ab45cd67eh"],
  "batchSize": 50
}

15. Create Filter (create_filter)

Creates a new Gmail filter with custom criteria and actions.

{
  "criteria": {
    "from": "newsletter@company.com",
    "hasAttachment": false
  },
  "action": {
    "addLabelIds": ["Label_Newsletter"],
    "removeLabelIds": ["INBOX"]
  }
}

16. List Filters (list_filters)

Retrieves all Gmail filters.

{}

17. Get Filter (get_filter)

Gets details of a specific Gmail filter.

{
  "filterId": "ANe1Bmj1234567890"
}

18. Delete Filter (delete_filter)

Deletes a Gmail filter.

{
  "filterId": "ANe1Bmj1234567890"
}

19. Create Filter from Template (create_filter_from_template)

Creates a filter using pre-defined templates for common scenarios.

{
  "template": "fromSender",
  "parameters": {
    "senderEmail": "notifications@github.com",
    "labelIds": ["Label_GitHub"],
    "archive": true
  }
}

20. Reply All (reply_all)

Replies to all recipients of an email. Automatically fetches the original email to build the recipient list and sets proper threading headers (In-Reply-To, References, threadId).

How it works:

1. Fetches the original email by messageId
2. Builds To from the original sender (From header)
3. Builds CC from original To + CC, excluding your own email
4. Sets threading headers so the reply lands in the correct thread
5. Sends via the existing send_email pipeline (supports attachments, HTML, multipart)

{
  "messageId": "182ab45cd67ef",
  "body": "Thanks for the update, everyone. I'll review and get back to you.",
  "mimeType": "text/plain"
}

With HTML and attachments:

{
  "messageId": "182ab45cd67ef",
  "body": "Plain text fallback",
  "htmlBody": "Thanks for the update. See attached notes.
",
  "mimeType": "multipart/alternative",
  "attachments": ["/path/to/notes.pdf"]
}

Parameters:

• messageId (required): ID of the email to reply to
• body (required): Reply body (plain text, or fallback when using multipart)
• htmlBody (optional): HTML version of the reply body
• mimeType (optional): text/plain (default), text/html, or multipart/alternative
• attachments (optional): Array of file paths to attach

Filter Management Features

Filter Criteria

You can create filters based on various criteria:

Criteria	Example	Description
from	"sender@example.com"	Emails from a specific sender
to	"recipient@example.com"	Emails sent to a specific recipient
subject	"Meeting"	Emails with specific text in subject
query	"has:attachment"	Gmail search query syntax
negatedQuery	"spam"	Text that must NOT be present
hasAttachment	true	Emails with attachments
size	10485760	Email size in bytes
sizeComparison	"larger"	Size comparison (larger, smaller)

Filter Actions

Filters can perform the following actions:

Action	Example	Description
addLabelIds	["IMPORTANT", "Label_Work"]	Add labels to matching emails
removeLabelIds	["INBOX", "UNREAD"]	Remove labels from matching emails
forward	"backup@example.com"	Forward emails to another address

Filter Templates

The server includes pre-built templates for common filtering scenarios:

1. From Sender Template (fromSender)

Filters emails from a specific sender and optionally archives them.

{
  "template": "fromSender",
  "parameters": {
    "senderEmail": "newsletter@company.com",
    "labelIds": ["Label_Newsletter"],
    "archive": true
  }
}

2. Subject Filter Template (withSubject)

Filters emails with specific subject text and optionally marks as read.

{
  "template": "withSubject",
  "parameters": {
    "subjectText": "[URGENT]",
    "labelIds": ["Label_Urgent"],
    "markAsRead": false
  }
}

3. Attachment Filter Template (withAttachments)

Filters all emails with attachments.

{
  "template": "withAttachments",
  "parameters": {
    "labelIds": ["Label_Attachments"]
  }
}

4. Large Email Template (largeEmails)

Filters emails larger than a specified size.

{
  "template": "largeEmails",
  "parameters": {
    "sizeInBytes": 10485760,
    "labelIds": ["Label_Large"]
  }
}

5. Content Filter Template (containingText)

Filters emails containing specific text and optionally marks as important.

{
  "template": "containingText",
  "parameters": {
    "searchText": "invoice",
    "labelIds": ["Label_Finance"],
    "markImportant": true
  }
}

6. Mailing List Template (mailingList)

Filters mailing list emails and optionally archives them.

{
  "template": "mailingList",
  "parameters": {
    "listIdentifier": "dev-team",
    "labelIds": ["Label_DevTeam"],
    "archive": true
  }
}

Common Filter Examples

Here are some practical filter examples:

Auto-organize newsletters:

{
  "criteria": {
    "from": "newsletter@company.com"
  },
  "action": {
    "addLabelIds": ["Label_Newsletter"],
    "removeLabelIds": ["INBOX"]
  }
}

Handle promotional emails:

{
  "criteria": {
    "query": "unsubscribe OR promotional"
  },
  "action": {
    "addLabelIds": ["Label_Promotions"],
    "removeLabelIds": ["INBOX", "UNREAD"]
  }
}

Priority emails from boss:

{
  "criteria": {
    "from": "boss@company.com"
  },
  "action": {
    "addLabelIds": ["IMPORTANT", "Label_Boss"]
  }
}

Large attachments:

{
  "criteria": {
    "size": 10485760,
    "sizeComparison": "larger",
    "hasAttachment": true
  },
  "action": {
    "addLabelIds": ["Label_LargeFiles"]
  }
}

Advanced Search Syntax

The search_emails tool supports Gmail's powerful search operators:

Operator	Example	Description
from:	from:john@example.com	Emails from a specific sender
to:	to:mary@example.com	Emails sent to a specific recipient
subject:	subject:"meeting notes"	Emails with specific text in the subject
has:attachment	has:attachment	Emails with attachments
after:	after:2024/01/01	Emails received after a date
before:	before:2024/02/01	Emails received before a date
is:	is:unread	Emails with a specific state
label:	label:work	Emails with a specific label

You can combine multiple operators: from:john@example.com after:2024/01/01 has:attachment

Advanced Features

Email Attachment Support

The server provides comprehensive attachment functionality:

• Sending Attachments: Include file paths in the attachments array when sending or drafting emails
• Attachment Detection: Automatically detects MIME types and file sizes
• Download Capability: Download any email attachment to your local filesystem
• Enhanced Display: View detailed attachment information including filenames, types, sizes, and download IDs
• Multiple Formats: Support for all common file types (documents, images, archives, etc.)
• RFC822 Compliance: Uses Nodemailer for proper MIME message formatting

Supported File Types: All standard file types including PDF, DOCX, XLSX, PPTX, images (PNG, JPG, GIF), archives (ZIP, RAR), and more.

Email Content Extraction

The server intelligently extracts email content from complex MIME structures:

• Prioritizes plain text content when available
• Falls back to HTML content if plain text is not available
• Handles multi-part MIME messages with nested parts
• Processes attachments information (filename, type, size, download ID)
• Preserves original email headers (From, To, Subject, Date)

International Character Support

The server fully supports non-ASCII characters in email subjects and content, including:

• Turkish, Chinese, Japanese, Korean, and other non-Latin alphabets
• Special characters and symbols
• Proper encoding ensures correct display in email clients

Comprehensive Label Management

The server provides a complete set of tools for managing Gmail labels:

• Create Labels: Create new labels with customizable visibility settings
• Update Labels: Rename labels or change their visibility settings
• Delete Labels: Remove user-created labels (system labels are protected)
• Find or Create: Get a label by name or automatically create it if not found
• List All Labels: View all system and user labels with detailed information
• Label Visibility Options: Control how labels appear in message and label lists

Label visibility settings include:

• messageListVisibility: Controls whether the label appears in the message list (show or hide)
• labelListVisibility: Controls how the label appears in the label list (labelShow, labelShowIfUnread, or labelHide)

These label management features enable sophisticated organization of emails directly through Claude, without needing to switch to the Gmail interface.

Batch Operations

The server includes efficient batch processing capabilities:

• Process up to 50 emails at once (configurable batch size)
• Automatic chunking of large email sets to avoid API limits
• Detailed success/failure reporting for each operation
• Graceful error handling with individual retries
• Perfect for bulk inbox management and organization tasks

Security Notes

• OAuth credentials are stored securely in your local environment (~/.gmail-mcp/)
• The server uses offline access to maintain persistent authentication
• Never share or commit your credentials to version control
• Regularly review and revoke unused access in your Google Account settings
• Credentials are stored globally but are only accessible by the current user
• Attachment files are processed locally and never stored permanently by the server

Troubleshooting

1. OAuth Keys Not Found

   • Make sure gcp-oauth.keys.json is in either your current directory or ~/.gmail-mcp/
   • Check file permissions

2. Invalid Credentials Format

   • Ensure your OAuth keys file contains either web or installed credentials
   • For web applications, verify the redirect URI is correctly configured

3. Port Already in Use

   • If port 3000 is already in use, please free it up before running authentication
   • You can find and stop the process using that port

4. Batch Operation Failures

   • If batch operations fail, they automatically retry individual items
   • Check the detailed error messages for specific failures
   • Consider reducing the batch size if you encounter rate limiting

5. Attachment Issues

   • File Not Found: Ensure attachment file paths are correct and accessible
   • Permission Errors: Check that the server has read access to attachment files
   • Size Limits: Gmail has a 25MB attachment size limit per email
   • Download Failures: Verify you have write permissions to the download directory

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

CI requires README updates — every push to main and every PR must include a README.md change (even a version bump or changelog entry). This ensures documentation stays current as the codebase evolves.

To bypass for commits that genuinely don't need a docs update (dependency bumps, CI config changes), include [skip-readme] or [no-readme] in your commit message or PR title.

Running evals

The evals package loads an mcp client that then runs the index.ts file, so there is no need to rebuild between tests. You can load environment variables by prefixing the npx command. Full documentation can be found here.

OPENAI_API_KEY=your-key  npx mcp-eval src/evals/evals.ts src/index.ts

License

MIT

Support

If you encounter any issues or have questions, please file an issue.