MCP Email Server

This Python script implements an MCP (Model Context Protocol) server using the mcp library (FastMCP) that allows an LLM (like Claude) to interact with an email account using POP3 (for reading/deleting emails) and SMTP (for sending emails), both secured with TLS encryption. It uses python-dotenv to load configuration from a .env file.

Features

• Poll Emails: Polls the inbox for email headers (pollEmails).
• Fetch Full Emails: Retrieves specific emails (headers and body) by ID (getEmailsById).
• Delete Emails: Deletes specific emails by ID (deleteEmailsById).
• Send Emails: Sends plain text (sendTextEmail) or HTML formatted (sendHtmlEmail) emails.
• Secure Connections: Uses POP3 over SSL (default port 995). For SMTP, supports both STARTTLS (explicit TLS, default port 587) and direct SSL/TLS (implicit TLS, default port 465), configurable via environment variable.
• Configuration: Loads credentials and server details from environment variables or a .env file.

Tools Provided

The server exposes the following tools (defined using @mcp.tool()) to the connected LLM:

1. pollEmails()

   • Description: Returns the message ID and key headers (Subject, From, Date, Message-ID) of all emails currently in the selected mailbox.
   • Inputs: None.
   • Returns: list[dict] - A list of dictionaries, each containing id and headers. Example: [{"id": 1, "Subject": "Hello", "From": "...", "Date": "...", "Message-ID": "..."}]

2. getEmailsById(ids: list)

   • Description: Returns the full details (ID, headers, parsed body) of the specified emails. It attempts to parse the body, preferring HTML over plain text if available.
   • Inputs:
     • ids (list[int]): A list of email IDs to retrieve (IDs correspond to the order returned by pollEmails at the time of polling).
   • Returns: list[dict] - A list of dictionaries, each containing id, headers (dict), and body (str). If an ID is invalid or fetching fails, an error key will be present. Example: [{"id": 1, "headers": {"Subject": "..."}, "body": "..."}]

3. deleteEmailsById(ids: list)

   • Description: Marks specified emails for deletion based on their ID. Important: Deleting emails invalidates the current ID sequence. It's recommended to perform deletions after all necessary read operations in a given session. The actual deletion occurs when the POP3 connection is closed after the command.
   • Inputs:
     • ids (list[int]): A list of email IDs to delete.
   • Returns: dict - A dictionary indicating which IDs were marked for deletion and which failed. Example: {"deleted": [1, 3], "failed": {2: "Error message"}}

4. sendTextEmail(fromAddress: str, toAddresses: list, subject: str, body: str)

   • Description: Sends a plain text email via SMTP.
   • Inputs:
     • fromAddress (str): The email address to send from. Note: Sending may fail if this doesn't match the authenticated user, depending on SMTP server policy.
     • toAddresses (list[str]): A list of recipient email addresses.
     • subject (str): The email subject line.
     • body (str): The plain text content of the email body.
   • Returns: dict - Status indication. Example: {"status": "success"} or {"error": "..."}

5. sendHtmlEmail(fromAddress: str, toAddresses: list, subject: str, body: str)

   • Description: Sends an HTML formatted email via SMTP.
   • Inputs:
     • fromAddress (str): The email address to send from. Note: Sending may fail if this doesn't match the authenticated user, depending on SMTP server policy.
     • toAddresses (list[str]): A list of recipient email addresses.
     • subject (str): The email subject line.
     • body (str): The HTML content of the email body.
   • Returns: dict - Status indication. Example: {"status": "success"} or {"error": "..."}

Setup and Installation

1. Prerequisites:

   • Python 3.12+ installed (check pyproject.toml for specific version, e.g., >=3.12).
   • uv installed (recommended for environment management and running).

2. Environment Setup & Dependencies:

   • Navigate to the email-mcp-server directory in your terminal.
   • Create and activate a virtual environment using uv:

     uv venv
     source .venv/bin/activate  # Linux/macOS
     # .venv\Scripts\activate  # Windows
     

   • Install dependencies using uv (it reads pyproject.toml and installs mcp and python-dotenv):

     uv pip install -e .
     # or 'uv pip sync' if uv.lock exists
     

     (This installs the package in editable mode, which is good practice for development).

3. Configuration (.env file):

   • Create a file named .env in the email-mcp-server directory.
   • Add your email credentials and server details to this file:

     EMAIL_USER=YourEmailUsername@example.com
     EMAIL_PASS=YourEmailAppPasswordOrRegularPassword
     POP3_SERVER=pop.example.com
     POP3_PORT=995 # Optional, defaults to 995
     
     # SMTP Configuration (Choose ONE method: STARTTLS or SSL)
     SMTP_SERVER=smtp.example.com
     # For STARTTLS (usually port 587, default method):
     SMTP_PORT=587 # Optional, defaults to 587 if SMTP_USE_SSL is false/unset
     # SMTP_USE_SSL=false # Optional, defaults to false
     
     # OR For direct SSL (usually port 465):
     # SMTP_PORT=465 # Optional, defaults to 465 if SMTP_USE_SSL is true
     # SMTP_USE_SSL=true
     

   • Security: Ensure the .env file is kept secure and never committed to version control (add .env to your .gitignore file).

4. Configuration (Claude Desktop):

   • Add this server to your Claude Desktop developer configuration file (developer_config.json).
   • Replace /path/to/email-mcp-server with the full, absolute path to the email-mcp-server directory on your system.
   • Note: The env section in the JSON is now less critical if you use a .env file, but it can still be used to override .env variables if needed.

   {
       "mcpServers": {
           "email-mcp-server": {
               "command": "uv",
               "args": [
                   "--directory",
                   "/path/to/email-mcp-server",
                   "run",
                   "main.py"
               ],
               "env": {
                   # These can override .env file settings if needed
                   # "EMAIL_USER": "...",
                   # "EMAIL_PASS": "...",
                   # "POP3_SERVER": "...",
                   # "POP3_PORT": "...",
                   # "SMTP_SERVER": "...",
                   # "SMTP_PORT": "...",
                   # "SMTP_USE_SSL": "false" # or "true"
               }
           }
       }
   }
   

5. Restart Claude Desktop: After modifying the configuration, restart Claude Desktop for the changes to take effect. The server should connect automatically.

Important Notes

• .env File: Using a .env file is the recommended way to manage credentials for this server.
• App Passwords: If your email provider uses Two-Factor Authentication (2FA), you will likely need to generate an "App Password" specifically for this server instead of using your regular account password. Use this App Password in your .env file for EMAIL_PASS. Consult your email provider's documentation (e.g., Gmail, Outlook).
• Security: Ensure the .env file and potentially the developer_config.json file are kept secure. Add .env to your .gitignore.
• Error Handling: The server uses the mcp library's error handling. Connection errors or tool execution failures should result in appropriate MCP error responses.
• Email IDs: POP3 email IDs are typically sequential numbers assigned by the server for the current session. They are only valid for the duration of that session and will change if emails are deleted. Use pollEmails to get current IDs before using getEmailsById or deleteEmailsById.