CoolUtils Mail Viewer

Mail Viewer MCP Server

A Model Context Protocol server that lets Claude, Cursor, Cline, and any MCP-compatible AI agent read, convert, and extract attachments from email files — .eml, .msg, .p7m, .mim, .tnef, .vcf, .olk15, and more.

The server is built into CoolUtils Mail Viewer — there is nothing extra to install. Run MailViewer.exe --mcp and the program skips its GUI to act as a stdio JSON-RPC server.

What you can do

Once connected, give your AI assistant natural-language instructions:

• "Convert all .msg files in D:\archive to PDF and put them in D:\output" — the agent calls convert_mail on each file.
• "What attachments does this EML have and who sent it?" — get_mail_info returns a clean JSON object instantly.
• "Extract all attachments from these 40 emails into C:\attachments" — extract_attachments saves them all in one pass.

Everything runs locally — your mail files are never uploaded anywhere.

Tools

convert_mail

Converts a mail file to the specified output format using the full Mail Viewer rendering engine.

• Source formats: .eml, .msg, .mim, .p7m, .vmbx, .tnef, .mapixml, .olk15, .vcf, .contact, .3uc
• Output formats: pdf, html, txt, doc, rtf, tiff, jpg, png, bmp, emf, eml, xps

PDF and DOCX output preserves embedded HTML, inline images, attachment previews, and message headers — identical to what you see in the GUI.

get_mail_info

Reads a mail file and returns its metadata as JSON: sender, To/CC/BCC recipients, subject, date, raw RFC headers, plain-text and HTML body, and a list of attachments with names, sizes, and content types. The source file is not modified.

extract_attachments

Saves all attachments from a mail file into a target folder (created automatically if it does not exist). Returns the list of saved files with absolute paths and sizes in bytes.

Full input/output schemas: schemas/mcp-tools.json.

Installation

1. Install Mail Viewer

Download and install CoolUtils Mail Viewer for Windows from https://www.coolutils.com/MailViewer. The MCP server is bundled inside the standard MailViewer.exe binary — no extra package, no separate license.

A 30-day free trial is available; no email or credit card is required.

2. Configure your MCP client

Claude Code

Add to ~/.claude.json under mcpServers:

{
  "mcpServers": {
    "mailviewer": {
      "command": "C:\\Program Files\\CoolUtils\\CoolUtils Mail Viewer\\MailViewer.exe",
      "args": ["--mcp"]
    }
  }
}

Claude Desktop

Add to %APPDATA%\Claude\claude_desktop_config.json under mcpServers (same block as above).

Cursor

Add to .cursor/mcp.json in your project, or to ~/.cursor/mcp.json globally — same JSON block.

Cline

Open Cline's MCP settings UI and paste the same block.

A copy-paste-ready snippet is also installed alongside the executable as claude-config-snippet.json. Adjust the path if you installed Mail Viewer in a non-default location.

3. Verify

Run this in a command prompt to confirm the server responds:

echo {"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2024-11-05","capabilities":{},"clientInfo":{"name":"t","version":"0"}}} | "C:\Program Files\CoolUtils\CoolUtils Mail Viewer\MailViewer.exe" --mcp

You should see a single JSON-RPC response containing protocolVersion, serverInfo, and a tools capability.

Example sessions

See examples/usage.md for end-to-end transcripts:

• Batch convert a folder — point Claude at a directory of .msg files and ask for PDFs.
• Forensic triage — ask Claude to summarize sender/subject/attachment patterns across 100 emails.
• Attachment harvesting — extract every attachment from a quarter's worth of legal correspondence into one folder.

Technical details

• Transport: stdio (NDJSON, one JSON-RPC 2.0 message per line, UTF-8)
• Protocol version: 2024-11-05
• Server name (reported in initialize): mailviewer-mcp
• Platform: Windows 7 / 8 / 10 / 11
• License: Commercial (Mail Viewer); MIT (this configuration/docs repo). Personal license starts at $49.90, 30-day free trial.

Server manifest: schemas/mcp-server.json.

Troubleshooting

The server doesn't respond. Verify the executable path is correct. The default install path on Windows is C:\Program Files\CoolUtils\CoolUtils Mail Viewer\MailViewer.exe. On 32-bit installs use C:\Program Files (x86)\….

Claude can't find the tools. Restart your MCP client after editing the config file. Check the client logs — for Claude Desktop, see %APPDATA%\Claude\logs.

File path errors. Use absolute paths in your prompts. Forward slashes (/) and backslashes (\) both work; quote paths with spaces.

Trial expired. Buy a license — Personal starts at $49.90. The MCP server keeps working in the same binary.

Resources

• Mail Viewer product page
• MCP article on coolutils.com
• Model Context Protocol specification
• CoolUtils support

License

The configuration files, schemas, and documentation in this repository are released under the MIT License. CoolUtils Mail Viewer itself is commercial software — see the product page for licensing.